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THE reported discovery of living bacteria in ancient rocks buried deep under Virginia evokes memories of bitter disputes after similar reports in the past. Mindful of this history, the experimenters have resorted to heroic efforts to avoid contamination.
In the mid-1960's, Dr. Bartholomew Nagy of Fordham University and colleagues reported extracting five types of "organized elements," resembling fossil bacteria, from within a meteorite that had fallen on France in 1864.
There was a rush to examine other meteorites of this type, and researchers around the world began reporting that they had found similar fossils or life's precursors. Among them were Dr. Melvin Calvin, a Nobel laureate at the University of California in Berkeley, and colleagues, who said they had found what seemed to be biological building blocks in meteorites. Another Nobel laureate, Dr. Harold C. Urey of the University of Chicago, urged that the reports be taken seriously.
Dr. Nagy pointed out that his examination of the French meteorites had sought valiantly to avoid contamination. Before a sample of the interior was extracted and studied, the equipment was cleaned with acid and baked in a vacuum, or kept red-hot for an hour.
Dr. Frederick Sisler, working in the Germ-Free Laboratory of the National Institutes of Health, said he was also culturing bacteria from a meteorite. All sides of the specimen's exterior were sterilized by exposure to intense ultraviolet light. The meteorite was then soaked in hydrogen peroxide to wash off dirt, held briefly over a flame and plunged into a germicidal solution.
In 1963 these and earlier reports were finally discredited when Dr. Edward Anders of the Enrico Fermi Institute for Nuclear Studies at the University of Chicago and a colleague showed that the most lifelike of Dr. Nagy's specimens were actually ragweed pollen grains.
Of the new claim, Dr. Anders, reached at his home in Switzerland, said he found it "quite intriguing."Continue reading the main story
To avoid contamination this time, the Department of Energy group took measures similar to those applied to rocks brought back from the Moon in 1969. Those specimens, and for a time, the astronauts themselves, were quarantined in a special building at the Johnson Space Center in Houston. The purpose was not only to see that no earth bacteria invaded the specimens before analysis, but to prevent the escape of any brought from the Moon.Continue reading the main story | <urn:uuid:ba81a5f8-007c-4c56-91c1-2fe4bab339c8> | 3.671875 | 499 | Truncated | Science & Tech. | 39.660323 | 95,507,119 |
Research by Austrian geneticists has raised the possibility that stem cells could be isolated from amniotic fluid – the protective bath water that surrounds the unborn baby.
Geneticist Professor Markus Hengstschläger and his team at the University of Vienna have isolated a subgroup of cells from amniotic fluid that express a protein called Oct-4 – known to be a key marker for human pluripotent stem cells.
Reporting the findings today (Monday 30 June) in Europes leading reproductive medicine journal Human Reproduction, Professor Hengstschläger stressed that the investigation was at an early stage. A lot more work had to be done to verify the finding, and tests were now under way to establish in which direction the cells could be differentiated. However, preliminary experiments have already provided evidence that they can be differentiated into nerve cells.
Margaret Willson | EurekAlert!
Colorectal cancer risk factors decrypted
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Algae Have Land Genes
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
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Most plants try to turn towards the sun. Scientists from the University of Gothenburg have worked with Finnish colleagues to understand how light-sensitive proteins in plant cells change when they discover light. The results have been published in the most recent issue of Nature.
The family of proteins involved is known as the “phytochrome” family, and these proteins are found in all plant leaves. These proteins detect the presence of light and inform the cell whether it is day or night, or whether the plant is in the shade or the sun.
“You can think of them as the plant’s ‘eyes’. Our study has shown how these eyes work at the molecular level,” explains Sebastian Westenhoff at the Department of Chemistry and Molecular Biology at the University of Gothenburg.
Molecules change in the light
Most plants try to avoid the shade and grow towards the light, which enables them, among other things, to consume more carbon dioxide through photosynthesis. Proteins known as “phytochromes” control this process. The phytochromes in the plants are thus changed through the light radiation, and signals are passed onwards to the cells.
Phytochromes have, as do most other proteins, a three-dimensional molecular structure. Light is absorbed by the phytochromes and the structure of the protein changes.
The scientists have studied this structural change in phytochromes from bacteria, since it is possible to obtain sufficient material to work on from bacteria.
“We already knew that some form of structural change was taking place, since the light signals must be transferred onwards to the cell. What we didn’t know, however, was how the structure changed, and this is what we have revealed. Nearly the complete molecule is rebuilt,” says Sebastian Westenhoff.
More efficient crops
The discovery increases our understanding of how phytochromes work. This may, in turn, lead to new strategies in the development of more efficient crops, which may be able to grow where there is little light.
“Proteins are the factories and machines of life, and their structures change when they carry out their specific tasks. At the moment, it’s usually not possible to determine these changes. But I believe that we can use similar experiments to determine many important structural changes in phytochromes and other proteins,” says Sebastian Westenhoff.
New measurement method
A new measurement method that Sebastian Westenhoff has developed has made the study possible. This method is based on using laser light to initiate the structural change. X-rays are then used to image the structural change.
The project has its origin in an approach made by scientist Janne Ihalainen from the University of Jyväslkyla two years ago.
“He asked whether we could use my method on phytochromes, which he had recently started working on.”
Link to the article: http://dx.doi.org/10.1038/nature13310
Sebastian Westenhoff, Department for Chemistry and Molecular Biology, University of Gothenburg
Tel: +46 31 786 3936, E-mail: email@example.com
Carina Eliasson | idw - Informationsdienst Wissenschaft
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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We all know that our region is facing enormous challenges as we grapple with flooding. While many factors such as development patterns and climate change affect flood risk, it comes down to how much rainfall we get and how runoff from storm events can be managed. Accurate information on rainfall amounts is essential to address these threats.
Surface-water reservoirs’ evaporative water losses aren’t the only reason that HARC President Jim Lester has been speaking out against over-reliance on such projects to meet Texas’ future water needs as the State Water Plan is implemented.
As Lester’s and other HARC scientists’ longstanding scientific involvement with coastal ecosystem issues has underscored, reservoirs can bring lasting environmental harm. Those impacts occur both in the immediate area where reservoirs are constructed along rivers and in the wildlife-rich bays and estuaries that those rivers nourish along the Texas coast.
Preventing that environmental damage at the same time that reservoir evaporation is avoided makes more sense to Lester. His recommendation – substituting underground water storage for some new reservoirs – is also in line with HARC’s mission of helping people thrive and helping nature flourish at the same time.
Lester’s recent public comments on the State Water Plan in interviews with reporters and a newspaper column have their roots in HARC’s continuing focus on coastal subjects, particularly around the Galveston Bay system.
“Texas has built so many reservoirs that have basically put the coast on a diet” in terms of the nutrients that rivers provide to bay ecosystems, he said. Bays and estuaries function as invaluable homes and nurseries for numerous coastal, marine and migrating wildlife species.
Every dam built in Texas reduces the volume of nutrients that flow downstream while trapping sediments that are part of the geological process that creates crucial natural formations such as deltas, estuaries and sandbars, he added.
Dam-blocked nutrients that formerly nourished coastal wildlife now feed the sport-fishing species such as Florida largemouth bass that have been stocked in the lakes created behind those dams.
Texas dams have been so effective at reducing nutrient flows to bays in the state that the excessively high levels of nutrients that damaged other coastal ecosystems such as Chesapeake Bay on the Atlantic Coast have never widely materialized in Texas, Lester said.
The coastal region fed by the Brazos River is the only one in Texas with a high-nutrient problem because there are no dams on that river near the coast, he said. By contrast, the Trinity River, a Galveston Bay tributary, has much lower nutrient levels below Lake Livingston than it does above the dam that created that reservoir.
Lester has served as an editor of two editions of “The State of the Bay,” a scientific report summarizing and assessing research findings about environmental trends in the Galveston Bay system. He is also currently vice-chair of the Trinity and San Jacinto Rivers and Galveston Bay Basin and Bay Expert Science Team, which advises state officials on how to manage flows in those rivers for the benefit of the organisms in those rivers and in the bay.
The Trinity-San Jacinto team’s recommendations were not as wildlife-friendly, in Lester’s opinion, as those produced by science teams for other rivers. He attributes the difference to the Trinity-San Jacinto team’s inclusion of engineers who work for the agencies that manage dams on those rivers along with wildlife biologists.
It was his experience on the Trinity-San Jacinto team that inspired Lester’s growing attention to the State Water Plan’s strong emphasis on building new reservoirs to serve future water needs in Texas.
Voters’ approval of funding for new reservoir proposals in the State Water Plan poses a dual concern, he explained: If Texas keeps damming rivers to meet its water needs, evaporation from reservoirs may reduce the hoped-for benefits. Meanwhile, those reservoirs may further reduce nutrients flowing into bays.
Some proposed reservoirs would also flood valuable riverside ecosystems, and Texas is “short on those good bottomland forests” already, because development has expanded into once-forested areas near rivers, he added. | <urn:uuid:6d33c8e7-5550-4389-af97-a485b32d6d26> | 3.375 | 868 | News (Org.) | Science & Tech. | 26.722446 | 95,507,204 |
Scientists have known that microbes living in the ground can play a major role in producing atmospheric carbon that can accelerate climate change, but now researchers from The University of Texas at Austin have discovered that soil microbes from historically wetter sites are more sensitive to moisture and emit significantly more carbon than microbes from historically drier regions. The findings, reported today in the Proceedings of the National Academy of Sciences, point the way toward more accurate climate modeling and improve scientists' understanding of distinct regional differences in microbial life.
Microbes in the soil add between 44 billion and 77 billion tons of carbon to the atmosphere each year -- more than all fossil fuels combined -- through a process called respiration. As the planet warms, soil respiration is expected to increase, but forecasters have had trouble accurately pinpointing by how much.
Microbes in the soil emit billions of tons of carbon into the atmosphere each year. A new study from The University of Texas at Austin finds that some microbes produce more atmospheric carbon than others, and that historic rainfall levels drive these microbes' response.
Courtesy of Pacific Northwest National Laboratory
The new research indicates that to do a better job of predicting changes in soil respiration, forecasters need to pay attention not only to climate change but also to climate history, as microbes respond differently to shifts in their environment in wetter versus drier areas.
In regions with more rainfall historically, soil microbes were found to respire twice as much carbon to the atmosphere as microbes from drier regions. Scientists determined that this was because the microbes responded differently to change: Those from the wettest areas were four times as sensitive to shifts in moisture as their counterparts from the driest areas.
"Current models assume that soil microbes at any site around the world exhibit the same responses to environmental change and do so instantaneously," says Christine Hawkes, a professor of integrative biology, "but we demonstrated that historical rainfall shapes the soil respiration response."
It is unclear whether the insight into how soil microbes respond to moisture would drastically change the results of worldwide climate modeling efforts, which, so far, have taken different approaches to estimating how soil respiration responds to moisture. Incorporating the new discovery into ecosystem models, however, could help improve predictions based on local or regional differences in soil respiration and climate history.
Hawkes and the team conducted three long-term studies involving field research and lab experiments occurring over six years. In each case, the finding was the same: Historical rainfall levels proved critical for how soil microbes would respond to change, affecting the outcome just as temperature does.
"You've heard of the crisis of replication? Well, we tested this three different ways, and we couldn't get the soils to do anything different," Hawkes says. "This suggests that rainfall legacies will constrain future soil function, but we need further study to figure out by how much and for how long."
The research also highlights previously unknown nuances about the communities of microbes living under ground. Simple and microscopic, microbes nonetheless possess distinctive traits. Through decomposition and respiration, soil microbes affect the balance between carbon trapped under ground and emitted into the atmosphere, and this balance is not the same from one regional community to the next, the UT Austin researchers learned. They examined soil collected at various spots in Texas along the Edwards Plateau and found that microbes from the driest soil samples (living in areas with one-quarter as much water as the microbes from the wettest soils) responded with a fraction of the carbon emissions their wet-soil cousins produced. These differences persisted regardless of other soil characteristics.
"Because microbes are small and enormously diverse, we have this idea that when the environment changes, microbes can rapidly move around or shift local abundances to track that environmental change," Hawkes said. "We discovered, however, that soil microbes and their functions are highly resistant to change. Resistance to environmental change matters because it means that previous local conditions will constrain how ecosystems function when faced with a shift in climate."
The paper's co-authors include two former graduate students of Hawkes' -- Bonnie Waring, now at Utah State University; and Jennifer Rocca, currently at Duke University -- as well as a former postdoctoral researcher, Stephanie Kivlin, now at the University of New Mexico and beginning at the University of Tennessee in January.
Support for the study was provided by the Department of Energy's National Institute for Climate Change Research and Texas Ecolab.
Christine Sinatra | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
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NYSCF researchers develop novel bioengineering technique for personalized bone grafts
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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Energy transformation, also termed as energy conversion, is the process of changing energy from one of its forms into another. In physics, energy is a quantity that provides the capacity to perform many actions—think of lifting or warming an object. In addition to being convertible, energy is transferable to a different location or object, but it cannot be created or destroyed.
Energy in many of its forms may be used in natural processes, or to provide some service to society such as heating, refrigeration, lightening or performing mechanical work to operate machines. For example, in order to heat your home, your furnace can burn fuel, whose chemical potential energy is thus converted into thermal energy, which is then transferred to your home's air in order to raise its temperature.
In another example, an internal combustion engine burns gasoline of cause pressure that pushes the pistons, thus performing work in order to accelerate your vehicle, ultimately converting the fuel's chemical energy to your vehicle's additional kinetic energy corresponding to its increase in speed.
- 1 Entropy and limitations in conversion of thermal energy to other types
- 2 Transformation of kinetic energy of charged particles to electric energy
- 3 History of energy transformation from the early universe
- 4 Examples
- 5 See also
- 6 References
Entropy and limitations in conversion of thermal energy to other types
Conversions to thermal energy (thus raising the temperature) from other forms of energy, may occur with essentially 100% efficiency (many types %, such as when potential energy is converted to kinetic energy as an object falls in vacuum, or when an object orbits nearer or farther from another object, in space.
Though, conversion of thermal energy to other forms, thus reducing the temperature of a system, has strict limitations, often keeping its efficiency much less than 100% (even when energy is not allowed to escape from the system). This is because thermal energy has already been partly spread out among many available states of a collection of microscopic particles constituting the system, which can have enormous numbers of possible combinations of momentum and position (these combinations are said to form a phase space). In such circumstances, a measure called entropy, or evening-out of energy distributions, dictates that future states of an isolated system must be of at least equal evenness in energy distribution. In other words, there is no way to concentrate energy without spreading out energy somewhere else.
Thermal energy in equilibrium at a given temperature already represents the maximal evening-out of energy between all possible states. Such energy is sometimes considered "degraded energy," because it is not entirely convertible a "useful" form, i.e. one that can do more than just affect temperature. The second law of thermodynamics is a way of stating that, for this reason, thermal energy in a system may be converted to other kinds of energy with efficiencies approaching 100%, only if the entropy (even-ness or disorder) of the universe is increased by other means, to compensate for the decrease in entropy associated with the disappearance of the thermal energy and its entropy content. Otherwise, only a part of thermal energy may be converted to other kinds of energy (and thus, useful work), since the remainder of the heat must be reserved to be transferred to a thermal reservoir at a lower temperature, in such a way that the increase in Entropy for this process more than compensates for the entropy decrease associated with transformation of the rest of the heat into other types of energy...... Examples
Transformation of kinetic energy of charged particles to electric energy
In order to make the energy transformation more efficient, it is desirable to avoid the thermal conversion. For example, the efficiency of nuclear energy reactors, where kinetic energy of nuclei is first converted to thermal energy and then to electric energy, lies around 35%. By direct conversion of kinetic energy to electric, i.e. by eliminating the thermal energy transformation, the efficiency of energy transformation process can be dramatically improved.
History of energy transformation from the early universe
Energy transformations in the universe over time are (generally) characterized by various kinds of energy which has been available since the Big Bang, later being "released" (that is, transformed to more active types of energy such as kinetic or radiant energy), when a triggering mechanism is available to do it.
Release of energy from gravitational potential: A direct transformation of energy occurs when hydrogen produced in the big bang collects into structures such as planets, in a process during which part of the gravitational potential is to be converted directly into heat. In Jupiter, Saturn, and Neptune, for example, such heat from continued collapse of the planets' large gas atmospheres continues to drive most of the planets' weather systems, with atmospheric bands, winds, and powerful storms which are only partly powered by sunlight, however, on Uranus, little of this process occurs.
On Earth a significant portion of heat output from interior of the planet, estimated at a third to half of the total, is caused by slow collapse of planetary materials to a smaller size, with output of gravitationally driven heat.
Release of energy from radioactive potential: Familiar examples of other such processes transforming energy from the Big Bang include nuclear decay, in which energy is released which was originally "stored" in heavy isotopes, such as uranium and thorium. This energy was stored at the time of these elements' nucleosynthesis, a process which ultimately uses the gravitational potential energy released from the gravitational collapse of type IIa supernovae, to store energy in the creation of these heavy elements before they were incorporated into the solar system and the Earth. Such energy locked into uranium is triggered for sudden-release in nuclear fission bombs, and similar stored energies in atomic nuclei are released spontaneously, during most types of radioactive decay. In such processes, heat from decay of these atoms of radioisotope in the core of the Earth is transformed immediately to heat. This heat in turn may lift mountains, via plate tectonics and orogenesis. This slow lifting of terrain thus represents a kind of gravitational potential energy storage of the heat energy. The stored potential energy may be released to active kinetic energy in landslides, after a triggering event. Earthquakes also release stored elastic potential energy in rocks, a kind of mechanical potential energy which has been produced ultimately from the same radioactive heat sources.
Thus, according to present understanding, familiar events such as landslides and earthquakes release energy which has been stored as potential energy in the Earth's gravitational field, or elastic strain (mechanical potential energy) in rocks. Prior to this, the energy represented by these events had been stored in heavy atoms (or in the gravitational potential of the Earth). The energy stored in heat atoms had been stored as potential ever since the time that gravitational potentials transforming energy in the collapse of long-destroyed stars (supernovae) created these atoms, and in doing so, stored the energy within.
Release of energy from hydrogen fusion potential: In other similar chain of transformations beginning at the dawn of the universe, nuclear fusion of hydrogen in the Sun releases another store of potential energy which was created at the time of the Big Bang. At that time, according to theory, space expanded and the universe cooled too rapidly for hydrogen to completely fuse into heavier elements. This resulted in hydrogen representing a store of potential energy which can be released by nuclear fusion. Such a fusion process is triggered by heat and pressure generated from gravitational collapse of hydrogen clouds when they produce stars, and some of the fusion energy is then transformed into sunlight. Such sunlight may again be stored as gravitational potential energy after it strikes the Earth, as (for example) snow-avalanches, or when water evaporates from oceans and is deposited high above sea level (where, after being released at a hydroelectric dam, it can be used to drive turbine/generators to produce electricity). Sunlight also drives many weather phenomena on Earth. An example of a solar-mediated weather event is a hurricane, which occurs when large unstable areas of warm ocean, heated over months, give up some of their thermal energy suddenly to power a few days of violent air movement. Sunlight is also captured by green plants as chemical potential energy, when carbon dioxide and water are converted into a combustible combination of carbohydrates, lipids, and oxygen. Release of this energy as heat and light may be triggered suddenly by a spark, in a forest fire; or it may be available more slowly for animal or human metabolism, when these molecules are ingested, and catabolism is triggered by enzyme action.
Through all of these transformation chains, potential energy stored at the time of the Big Bang is later released by intermediate events, sometimes being stored in a number of ways over time between releases, as more active energy. In all these events, one kind of energy is converted to other types of energy, including heat.
Examples of sets of energy conversions in machines
For instance, a coal-fired power plant involves these energy transformations:
- Chemical energy in the coal converted to thermal energy in the exhaust gases of combustion.
- Thermal energy of the exhaust gases converted into thermal energy of steam through the heat exchanger.
- Thermal energy of steam converted to mechanical energy in the turbine.
- Mechanical energy of the turbine converted to electrical energy by the generator, which is the ultimate output
In such a system, the first and fourth step are highly efficient, but the second and third steps are less efficient. The most efficient gas-fired electrical power stations can achieve 50% conversion efficiency. Oil- and coal-fired stations achieve less.
In a conventional automobile, these energy transformations are involved:
- Chemical energy in the fuel converted to kinetic energy of expanding gas via combustion
- Kinetic energy of expanding gas converted to linear piston movement
- Linear piston movement converted to rotary crankshaft movement
- Rotary crankshaft movement passed into transmission assembly
- Rotary movement passed out of transmission assembly
- Rotary movement passed through differential
- Rotary movement passed out of differential to drive wheels
- Rotary movement of drive wheels converted to linear motion of the vehicle.
Other energy conversions
There are many different machines and transducers that convert one energy form into another. A short list of examples follows:
- Thermoelectric (Heat → Electric energy)
- Geothermal power (Heat→ Electric energy)
- Heat engines, such as the internal combustion engine used in cars, or the steam engine (Heat → Mechanical energy)
- Ocean thermal power (Heat → Electric energy)
- Hydroelectric dams (Gravitational potential energy → Electric energy)
- Electric generator (Kinetic energy or Mechanical work → Electric energy)
- Fuel cells (Chemical energy → Electric energy)
- Battery (electricity) (Chemical energy → Electric energy)
- Fire (Chemical energy → Heat and Light)
- Electric lamp (Electric energy → Heat and Light)
- Microphone (Sound → Electric energy)
- Wave power (Mechanical energy → Electric energy)
- Windmills (Wind energy → Electric energy or Mechanical energy)
- Piezoelectrics (Strain → Electric energy)
- Friction (Kinetic energy → Heat)
- Electric heater (Electric energy → Heat)
- Photosynthesis (Electromagnetic radiation → Chemical energy)
- ATP hydrolysis (Chemical energy in adenosine triphosphate → mechanical energy)
- Dunbar, W.; Mooby, S.; et., al. (1995). "Exergy analysis of an operating boiling-water-reactor nuclear power station". Energy Conversion and Management. 36. doi:10.1016/0196-8904(94)00054-4.
- Wilson, P.D. (1996). .The Nuclear Fuel Cycle: From Ore to Waste. New York: Oxford University Press.
- Shinn, E.; et., al. (2012). "Nuclear energy conversion with stacks of graphene nanocapacitors". Complexity. Bibcode:2013Cmplx..18c..24S. doi:10.1002/cplx.21427. | <urn:uuid:ba764a5c-b4b2-4e52-861a-d81a872703f2> | 3.796875 | 2,503 | Knowledge Article | Science & Tech. | 20.20009 | 95,507,266 |
New research gives insight into a recent experiment that was able to manipulate an unprecedented number of atoms through a quantum simulator. This new theory could provide another step on the path to creating the elusive quantum computers.
An international team of researchers, led by the University of Leeds and in cooperation with the Institute of Science and Technology Austria and the University of Geneva, has provided a theoretical explanation for the particular behaviour of individual atoms that were trapped and manipulated in a recent experiment by Harvard University and MIT. The experiment used a system of finely tuned lasers to act as "optical tweezers" to assemble a remarkably long chain of 51 atoms.
When the quantum dynamics of the atom chain were measured, there were surprising oscillations that persisted for much longer than expected and which couldn't be explained.
Study co-author, Dr Zlatko Papic, Lecturer in Theoretical Physics at Leeds, said: "The previous Harvard-MIT experiment created surprisingly robust oscillations that kept the atoms in a quantum state for an extended time. We found these oscillations to be rather puzzling because they suggested that atoms were somehow able to "remember" their initial configuration while still moving chaotically.
"Our goal was to understand more generally where such oscillations could come from, since oscillations signify some kind of coherence in a chaotic environment - and this is precisely what we want from a robust quantum computer. Our work suggests that these oscillations are due to a new physical phenomenon that we called 'quantum many-body scar'."
In everyday life, particles will bounce off one another until they explore the entire space, settling eventually into a state of equilibrium. This process is called thermalisation. A quantum scar is when a special configuration or pathway leaves an imprint on the particles' state that keeps them from filling the entire space. This prevents the systems from reaching thermalisation and allows them to maintain some quantum effects.
Dr Papic said: "We are learning that quantum dynamics can be much more complex and intricate than simply thermalisation. The practical benefit is that extended periods of oscillations are exactly what is needed if quantum computers are to become a reality. The information processed and stored on these computers will be dependent on keeping the atoms in more than one state at any time, it is a constant battle to keep the particles from settling into an equilibrium."
Study lead author, Christopher Turner, doctoral researcher at the School of Physics and Astronomy at Leeds, said: "Previous theories involving quantum scars have been formulated for a single particle. Our work has extended these ideas to systems which contain not one but many particles, which are all entangled with each other in complicated ways. Quantum many-body scars might represent a new avenue to realise coherent quantum dynamics."
The quantum many-body scars theory sheds light on the quantum states that underpin the strange dynamics of atoms in the Harvard-MIT experiment. Understanding this phenomenon could also pave the way for protecting or extending the lifetime of quantum states in other classes of quantum many-body systems. | <urn:uuid:656518ae-2737-4aa9-9eca-c82d25024fef> | 3.5 | 607 | News Article | Science & Tech. | 23.377484 | 95,507,269 |
Some helpers for fun Haskell programming with kids.
|say "lol"||says "lol" aloud (uses the command line say)|
|p "lol"||prints "lol" as text|
|i||reads a line of input from the user|
|w 1||waits one second|
|s [w 1, say "lol"]||run commands sequentially|
|rnd 4||generates random number between 1 and 4|
Have a look at the Guess example program. You can run it with | <urn:uuid:27d20073-f43c-432b-a7a7-12f9d7eee6ba> | 3.171875 | 113 | Product Page | Software Dev. | 65.330882 | 95,507,283 |
If a prairie chicken clucks in the prairie and no one is around to hear it, does it make a sound? Thanks to the innovative survey techniques deployed by the NRI research team of Dr. Brian Pierce, Frank Cartaya and Sarah Turner, we finally have our answer. Travel to eastern New Mexico with us in this week's blog as we track the team's progress while they conduct surveys using acoustic technology, which is 50 times more efficient than traditional methods for detecting the occurrence of the formerly ESA-listed Lesser Prairie Chicken (Tympanuchus pallidicintus) on Melrose Air Force Range. This is what raising the bar for the standards of proactive wildlife management looks like.
Posts tagged with endangered species. View all posts
Brown-headed cowbirds are obligate brood parasites, meaning they lay their eggs in the nests of other songbirds instead of building their own. Learn about trapping efforts to control this species in our Map of the Month and accompanying article.
Freshwater mussels play an important role in the health of freshwater ecosystems by providing food and habitat for other aquatic species, stabilizing stream bottoms, and filtering the water in our lakes and rivers. The Rio Grande basin is home to three mussel species suffering from habitat loss and growing human populations in this area may be threatening the water systems necessary for their survival.
The Texas A&M University Key deer team was recently honored by the U.S. Fish and Wildlife Service (USFWS) Southeast Region as a 2016 Regional Recovery Champion.
A first-in-the-nation conservation plan, crafted by the U.S. Department of Defense, U.S. Fish and Wildlife Service (USFWS) and wildlife agencies in Alabama, Florida, Georgia and South Carolina, protects at-risk gopher tortoises while helping military bases to continue training and testing missions across the tortoise’s Southern turf.
After being eradicated from the United States for more than 30 years, New World screwworm flies reappeared in the lower Florida Keys this year. Screwworms have infested the endangered Florida Key deer population, which is spread across 11 islands. Approximately 130 deer, mostly males, have been killed by or euthanized due to the infestation, according to researchers.
While many people try to avoid snakes, a group of researchers are doing everything they can to find snakes, specifically the rare Louisiana pine snake.
The nonvenomous, 6-foot-long snake lives in gopher burrows, coming out only to go from one burrow to another or to mate. Its only habitat is the longleaf pine savannahs in eastern Texas and western Louisiana. But today, that habitat is almost gone, said Dr. Toby Hibbitts, a researcher at the Texas A&M Institute of Renewable Natural Resources (IRNR) and curator of amphibians and reptiles at the Biodiversity Research and Teaching Collections at Texas A&M.
“With the loss of habitat, populations are crashing in Texas and Louisiana,” Hibbitts said.
The snake’s numbers have never been that abundant, Hibbitts said. In fact, the snake was undiscovered until the 1920s.
Based on her extensive avian research record, one might assume Dr. Ashley Long, Texas A&M Institute of Renewable Natural Resources (IRNR) research scientist, has been fascinated with birds her whole life. However, Long’s interest in ecology and wildlife didn’t begin until she was in college. | <urn:uuid:5bfe02ee-fd06-48d6-880d-2064306a8ba1> | 2.515625 | 732 | Content Listing | Science & Tech. | 43.649439 | 95,507,284 |
Hayward, Bruce W; Sabaa, Ashwaq T; Kawagata, Shungo; Grenfell, Hugh R (2009): Benthic foraminifera of Mediterranean deep-sea sediments. PANGAEA, https://doi.org/10.1594/PANGAEA.773782, Supplement to: Hayward, BW et al. (2009): The Early Pliocene re-colonisation of the deep Mediterranean Sea by benthic foraminifera and their pulsed Late Pliocene-Middle Pleistocene decline. Marine Micropaleontology, 71(3-4), 97-112, https://doi.org/10.1016/j.marmicro.2009.01.008
Always quote above citation when using data! You can download the citation in several formats below.
Ninety-five species and 19 genera of cosmopolitan, deep-sea benthic foraminifera belonging to the families Pleurostomellidae, Stilostomellidae and Nodosariidae, became extinct during the Late Pliocene-Middle Pleistocene. Only 50% of these (44 species) were present in the Pliocene or Pleistocene of the deep Mediterranean Sea (ODP Sites 654, 966, 967, 975, 976), being those which had successfully migrated in via the Strait of Gibraltar from the deep Atlantic following the annihilation of the Mediterranean deep-sea fauna during the Late Miocene Messinian Crisis. Most colonisation occurred within the first 0.8 myrs (5.3-4.5 Ma) after re-establishment of the Mediterranean-Atlantic link, with possibly a second lesser period of immigration in the Late Pliocene (3.4-3.0 Ma). We infer that colonisations may have been fortuitous and few in number, as some common members of the group in the Atlantic never succeeded in establishing in the Mediterranean Sea. There is no evidence of any new immigration events during the Pleistocene, implying that the present anti-estuarine circulation may have been in place throughout this period. Our studies suggest that these deep-water, low-oxygen-tolerant foraminifera survived the many periods of deep-water sapropel formation in the Pliocene-Early Pleistocene, possibly in somewhat shallower (~ 500 m) refuges with dysoxic, rather than anoxic conditions.
The Pliocene-Pleistocene stratigraphic record of this group of elongate, cylindrical benthic foraminifera with constricted and specialised apertures is similar in the west and east Mediterranean basins. The group declined in abundance (flux) and diversity in two pulses, during the Late Pliocene (3.1-2.7 Ma) and the late Early Pleistocene (1.3-1.0 Ma) in concert with global, southern-sourced, deep-water sites (AABW, CPDW) and earlier than the single decline (1.0-0.6 Ma) in global, intermediate water sites (uNADW, AAIW). All species, with one possible exception, disappeared earlier in the Mediterranean than globally. The highest occurrence of any species of this group in Mediterranean sites was 0.8-0.43 Ma, comparable with 0.7-0.2 Ma outside with the youngest survivors being in abyssal, deep-water.
Thus, despite the unusual oceanographic conditions and isolation, the deep Mediterranean Sea was in this case neither the centre for the evolution of new species nor a refuge where species survived after they had disappeared elsewhere.
Median Latitude: 36.709098 * Median Longitude: 15.264224 * South-bound Latitude: 33.796100 * West-bound Longitude: -4.312210 * North-bound Latitude: 40.579300 * East-bound Longitude: 32.725300
Date/Time Start: 1986-02-03T10:40:00 * Date/Time End: 1995-06-03T11:45:00
107-654A * Latitude: 40.579300 * Longitude: 10.696700 * Date/Time Start: 1986-02-03T10:40:00 * Date/Time End: 1986-02-08T15:15:00 * Elevation: -2208.0 m * Penetration: 473.8 m * Recovery: 239.84 m * Location: Tirreno Sea * Campaign: Leg107 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 52 cores; 473.8 m cored; 0 m drilled; 50.6 % recovery
160-966B * Latitude: 33.796100 * Longitude: 32.701400 * Date/Time Start: 1995-03-27T21:46:00 * Date/Time End: 1995-03-28T13:12:00 * Elevation: -927.0 m * Penetration: 146 m * Recovery: 96.5 m * Location: Eastern Basin * Campaign: Leg160 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 16 cores; 146 m cored; 0 m drilled; 66.1 % recovery
160-967A * Latitude: 34.068300 * Longitude: 32.725300 * Date/Time Start: 1995-04-01T23:50:00 * Date/Time End: 1995-04-02T11:40:00 * Elevation: -2553.0 m * Penetration: 141.3 m * Recovery: 142.14 m * Location: Eastern Basin * Campaign: Leg160 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 16 cores; 141.3 m cored; 0 m drilled; 100.6 % recovery | <urn:uuid:f3016178-7c02-4603-9785-91612364361e> | 2.765625 | 1,273 | Academic Writing | Science & Tech. | 63.77444 | 95,507,296 |
Check out the live demo
This project is an experiment in client-side data processing and visualization. Most of the code in this project is taken from https://github.com/cambecc/earth and has been re-purposed to support easier application to a variety of mapping APIs and Frameworks.
How it works
Windy which takes the bounds of the map, the data, and the canvas element and then applies a Bilinear Interpolation to generate a smooth surface. Once the surface has been generated a function randomly places "particles" onto the canvas at random x/y points. Each particle is then "evolved", moving in a direction and at a velocity dictated by the interpolated surface.
Before GFS data can be used with this code it has to be converted into JSON. To do this we used another awesome project by @cambecc called
grib2json. That tool converts data in the GRIB2 file format into a JSON structure with the grid represented as an array. An example result of that tool can be seen in the
Find a bug or want to request a new feature? Please let us know by submitting an issue.
Esri welcomes contributions from anyone and everyone. Please see our guidelines for contributing.
This project inherits an MIT license from cambecc/earth because 95% of the code here was copied from that project.
A copy of the license is available in the repository's license.txt file. | <urn:uuid:5b0c3ca8-fb9d-4fe2-aeac-b2cb7bbe247c> | 2.890625 | 303 | Product Page | Software Dev. | 50.618388 | 95,507,335 |
Slowing coral growth will cause Great Barrier Reef to 'fall apart'
Coral growth in Australia's Great Barrier Reef has fallen to its lowest rate for 400 years, in a troubling sign for the world's oceans, researchers have warned.
This could threaten a variety of marine ecosystems that rely on the reef and signal problems for other such organisms worldwide.
The Great Barrier Reef is the world's largest coral expanse, and like similar reefs worldwide is threatened by climate change and pollution.
A scientist from Queensland University studies bleached coral at the Keppel Islands on the southern Great Barrier Reef. Bleaching is a sign of corals responding to stress
A team from the Australian Institute of Marine Science studied 328 large coral colonies from 69 reefs.
They found the process of calcification, which gives the reefs their strength and structure, had declined by 13.3 per cent since 1990.
At this rate, the process of reef-building may stop as early as 2035, causing them to fall apart.
'The reefs will slowly break down, be taken over by algae,' lead researcher Glen De'ath said.
'The reef will still exist, but will be very different and far less diverse.'
An aerial view of the Great Barrier Reef: If the reef structure does break down, it would have a devastating effect on marine life
This would have a devastating effect on the fish and sealife that use the underwater rocky gardens as nurseries and shelters.
Coral reefs are delicate undersea structures made by tiny animals called coral polyps. They protect coastlines, provide a critical source of food for millions of people, attract tourists and are potential storehouses of medicines for cancer and other diseases.
'These organisms are central to the formation and function of ecosystems and food webs, and precipitous changes in the biodiversity and productivity of the world's oceans may be imminent,' the researchers wrote in the journal Science.
The team blamed a combination of global warming, ocean acidity level and decreasing carbonate content in seawater for the decline, unprecedented over the past 400 years.
'Verification of the causes of this decline should be made a high priority,' they added.
Coral covers about 400,000 square km (154,000 sq miles) of tropical ocean floor, but needs sustained sunlight, warmer waters and high levels of carbonate to flourish.
The biggest is Australia's Great Barrier Reef, a collection of 2,900 reefs along 2,100 km (1,300 miles) of Australia's northeast coast in a marine park the size of Germany.
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Sonar images revealed that, in some places, ocean currents have driven the mud along the Arctic Ocean bottom into piles, with some “mud waves” nearly 100 feet across.
Around the world, strong currents often create a wavy surface on the ocean bottom. But scientists previously thought the Arctic Ocean was too calm to do so.
Leonid Polyak, a research scientist at Byrd Polar Research Center at Ohio State University, said that it's too early to know how the waves formed.
“The mud waves could be caused by tidal fluctuations,” he said. “But that's really just speculation at this point.”
Polyak was one of the leaders of an international scientific expedition that crossed the Arctic Ocean in 2005, and he was part of a recent icebreaker expedition in 2007. Both missions took images of the ocean bottom with sonar and drew sediment cores from the ocean bottom.
Now that the sediment cores -- more than 1,000 feet in total -- are stored in a refrigerated facility of the Byrd Polar Research Center on the Ohio State campus, Polyak and his colleagues have begun their analysis.
Martin Jakobsson of Stockholm University in Sweden -- a team member and leader of the geology party in the 2007 expedition -- summarized the early findings of both sonar surveys Thursday, December 13, 2007, at the American Geophysical Union meeting in San Francisco . The presentation was part of a session on Arctic Ocean environmental history, and a related poster session was scheduled for Friday morning.
The 2005 Healy-Oden Trans-Arctic Expedition (HOTRAX) -- a cooperative effort between the United States Coast Guard Cutter Healy and the Swedish icebreaker Oden -- was the first scientific expedition to transit the entire Arctic Ocean in the direction from Alaska to Scandinavia . The scientists took sediment cores from 29 sites along the way.
For the 2007 Lomonosov Ridge off Greenland (LOMROG) expedition, the Oden joined with a Russian nuclear icebreaker called 50 let Pobedy (“50 Years of Victory”) to explore a smaller, difficult to access region of the Arctic Ocean near Greenland.
Both expeditions took images of the ocean bottom with a sonar system that also allowed them to view layers of sediment up to 1000 feet below ground.
The purpose of HOTRAX and LOMROG was to gather a sediment record of how the Arctic has changed over time, and also to find evidence of the ancient ice sheets that helped shape the Arctic Ocean seafloor. Scientists hope to use what they learned to better understand how water is exchanged between the basins, and how the Arctic affects (and is affected by) global climate systems.
This is a critical time for the Arctic, Polyak said. In the summer of 2007, much less ice covered the region than during any other time in the last century.
“Even a couple of years ago, we wouldn't have predicted that so little ice would cover the Arctic Ocean ,” he said. “It really looks like we may be living in a completely different world 20 to 30 years from now, with no ice in the Arctic in summer at all.”
The expeditions proved that giant ice masses once covered the arctic -- ice flows massive enough to scrape the ocean bottom half a mile deep. Sonar clearly showed the parallel grooves that ice flows carved in the sea floor, and boulders and other debris that the ice left behind.
As the scientists study the sediments and images in detail, they will focus on more recent Earth history -- specifically the last 150,000 years -- to find out how conditions during warm periods in the recent past resemble what we will likely have in the near future.
The mud waves that they spied on the ocean floor are another mystery, one that the scientists haven't begun to probe.
“Frankly, we have so much material to go through, and we've only just started,” Polyak said. “The goal is to establish a climate record in the sediments. To figure it out, we'll go through the cores centimeter by centimeter.”
The 2005 expedition was funded by the National Science Foundation, the Swedish Polar Research Secretariat, and the Swedish Science Council.
Leonid Polyak | EurekAlert!
Global study of world's beaches shows threat to protected areas
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
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|Specimen of Mycocepurus smithii|
|Distribution of Mycocepurus smithii|
Mycocepurus smithii is a species of fungus-growing ants from Latin America. This species is geographically widely distributed and can be found from Mexico in the north to Argentina in the south. Mycocepurus smithii was also found on some Caribbean Islands. It tends to be found in a variety of forested habitats and associated open areas. Two studies published in 2009 demonstrated that some populations of the species consist exclusively of females which reproduce via thelytokous parthenogenesis. A detailed study found evidence of sexual reproduction in some populations in the Brazilian Amazon. Accordingly, M. smithii consists of a mosaic of sexually and asexually reproducing populations. In asexual populations all ants in a single colony are female clones of the queen. Inside the colony, the ants cultivate a garden of fungus grown with pieces of dead vegetable matter, dead insects, and insect droppings.
Ants of the genus Mycocepurus are distinctly recognizable for the crown-like cluster of spines on their promesonotum, the fused mesonotum and pronotum on the front of their mesosoma or midsection. Mycocepurus smithii has sharp, protruding propodeal (posterior of the alitrunk) spines unlike M. obsoletus whose propodeal spines are blunt. Workers also do not have developed promesonotal spines in the center of their crown, which separates M. smithii from M. goeldii and similar species.
Initially, M. smithii was thought to only reproduce asexually because no evidence of male individuals had been found. This led to M. smithii being recognized as the first fungus-growing ant species to reproduce via thelytokous parthenogenesis, where females, the workers and reproductive queens, are produced asexually. The cytogenetic mechanism of thelytoky is either apomixis (mitotic parthenogenesis) or automixis with central fusion and low recombination rates. Automixis with central fusion is the cytogenetic mechanism that was recorded in other asexual ant species. Nests with multiple dealated queens are often found, suggesting that M. smithii is a polygynous species. This appears to be a case of secondary polygyny, and the queens may be daughters of the foundress.
A detailed study of many M. smithii populations across their geographic distribution range (Mexico to Argentina) showed that some M. smithii populations in the Brazilian Amazon reproduce sexually. This was demonstrated using highly variable genetic markers. Sperm was also found stored in the spermathecas of queens. Sexual reproduction was suggested as a mechanism for maintaining the genetic diversity seen in this species. In summary, M. smithii is not purely asexual, but instead consists of a “mosaic” of sexual and asexual populations. Phylogenetic reconstructions and the biology of the species suggest that these sexual populations gave rise to the asexual ones. The mechanism behind the shift to asexuality is still unknown. However, antibiotic assays and genetic screenings suggest that it is not an endosymbiont such as Wolbachia causing the asexuality. In fact, a comparative analysis showed that Wolbachia endosymbionts do not seem to cause asexuality in ants in general.
The nests and colonies of M. smithii were studied in great detail in Puerto Rico and Brazil. On the surface, M. smithii nests can be recognized by their nest mounds consisting of excavated soil and clay. A nest entrance of roughly 1.2 mm in diameter is located in the center of each nest mound. Large M. smithii nests, which are presumably older, can contain up to 7 or so chambers. Some fungus chambers are shallow whereas others can be found in great depths, as deep as 2 meters. The abandoned chambers are used to deposit waste from the fungus garden and loose soil from chamber construction. The number of nest chambers tends to increase as colonies grow older. Because M. smithii queens are capable of asexual reproduction, it is believed that colonies can also grow by budding in addition to independent colony foundation. Colonies that grow by budding can result in large colony networks.
Workers of M. smithii ants maintain narrow tunnels (diameter of 1.3 mm), which do not allow two ants to pass each other in the tunnel (head size is around 0.7 mm for workers and 0.9 mm for queens). The tunnels also have a number of slightly larger sections (about 3.6 mm diameter), which would allow passing while also facilitating information exchange. Narrow tunnels are presumably easier (energetically cheaper) to construct and may also aide in leveling the humidity or temperature of the colony or preventing predatory intrusions. In general, M. smithii colonies are smaller than the colonies of M. goeldii.
When founding a new colony, young queens either shed their wings prior to excavating the nest or just inside. They then excavate a tunnel to a depth of roughly 10 cm (4 in) and create a primary chamber. The dealate, or wingless, queen then carries the wings into the primary chamber and inserts them into the chamber ceiling where the surface of the wings is used as a platform for growing an incipient fungus garden. She will also forage around the nest entrance for caterpillar droppings to feed the fungus garden. The female fore wings of all so-called Paleoattini (the genera Mycocepurus, Apterostigma, and Myrmicocrypta) have a crescent-shaped spot lacking any veins, hairs, and pigmentation, and is thought to provide an “easy to clean” platform for the fungus garden. Queens of the socially parasitic species Mycocepurus castrator do not found their colonies independently, and the clear spot is absent from their wings. This indirectly supports the idea that the wing spot has a function during the early colony founding and fungus cultivation stage of independently founding Mycocepurus queens. As the colony matures, workers develop and then tend to the fungus garden, feeding it dried leaves, caterpillar droppings, and other debris from the leaf-litter.
One trait of M. smithii's fungus cultivation is that, unlike higher attines, they use a wide diversity of fungal lineages for their gardens. Lineages of M. smithii have undergone many cultivar shifts over time. This tendency to shift cultivars is hypothesized to be a mechanism for helping to offset some of the costs of asexuality. Also unlike other fungus-growing ants M. smithii has a microbiome that is distinct from the surrounding soil. A Brazilian population of M. smithii has a fungal cultivar with gongylidia-like structures. This is unusual, because gongylidia are the nutrient rich food bodies produced by the fungi of leaf-cutting ants – and leaf-cutting ants are rather distant relatives of Mycocepurus.
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- Mueller, UG; Rehner, SA; Schultz, TD (1998). "The evolution of agriculture in ants". Science. 281: 2034–2038. doi:10.1126/science.281.5385.2034.
- Rabeling, C. (2004). Nester, Streueintrag und symbiontische Pilze amazonischer Ameisen der Gruppe ursprünglicher Attini. Diplomarbeit. Universität Tübingen. 86p.
- Kellner, K; Fernandez-Marin, H; Ishak, H; Sen, R; Linksvayer, TA; Mueller, UG (2013). "Co-evolutionary patterns and diversification of ant-fungus associations in the asexual fungus-farming ant Mycocepurus smithii in Panama". Journal of Evolutionary Biology. 26 (6): 1352–1362. doi:10.1111/jeb.12140.
- Kellner, K; Ishak, HD; Linksvayer, TA; Mueller, UG (2015). "Bacterial community composition and diversity in an ancestral ant fungus symbiosis". FEMS Microbiology Ecology. 91 (7). doi:10.1093/femsec/fiv073.
- Masiulionis, VE; Rabeling, C; De Fine Licht, HH; Schultz, T; Bacci, M Jr. (2014). "A Brazilian Population of the Asexual Fungus-Growing Ant Mycocepurus smithii (Formicidae, Myrmicinae, Attini) Cultivates Fungal Symbionts with Gongylidia-Like Structures". PLoS ONE. 9 (8). doi:10.1371/journal.pone.0103800.
- Media related to Mycocepurus smithii at Wikimedia Commons
- Photograph of Mycocepurus smithii at myrmecos.net
- Taxonomic Information and Synonymy of Mycocepurus smithii at antcat.org
- Further Information About Mycocepurus smithii at antwiki.org
- Further Information About the Distribution and Biology of Mycocepurus smithii at antweb.org | <urn:uuid:3986c63b-b418-4c3f-9cfd-c77214283800> | 2.90625 | 2,838 | Knowledge Article | Science & Tech. | 51.271268 | 95,507,381 |
Geographic range size, seedling ecophysiology and phenotypic plasticity in Australian Acacia species
- Publication Type:
- Journal Article
- Journal of Biogeography, 2005, 32 (2), pp. 341 - 351
- Issue Date:
Aim: The degree to which eco-physiological traits critical to seedling establishment are related to differences in geographic range size among species is not well understood. Here, we first tested the idea that seedling ecophysiological attributes associated with establishment differ between narrowly distributed and geographically widespread plant species. Secondly, we tested the notion that species occupying wide geographic ranges have greater phenotypic plasticity in response to the environment than contrasted species with more restricted distributions. Location: Eastern Australia. Methods: We compared five pairs of geographically restricted and widespread Acacia species grown under glasshouse conditions for differences in seedling relative growth rate and associated allocational, morphological and physiological traits. We then examined whether widespread species displayed greater phenotypic plasticity in these traits than narrowly distributed species in response to changes in soil water availability. Results: Neither relative growth rate nor any measure of biomass accumulation or allocation differed significantly between seedlings of narrowly distributed and widespread species. In addition, the plasticity of biomass allocation was not greater in widespread species. However, the leaflets of widespread species had higher photosynthetic capacity and greater plasticity of water use efficiency than the leaflets of narrowly distributed species. Main conclusions: We demonstrated fundamental differences in the physiology and plasticity of leaflets of widespread and narrowly distributed species. The greater plasticity of these seedling leaflet traits may allow widespread Acacia species to utilize a wider range of environmental conditions in relation to soil moisture than restricted Acacia species. However, we did not find corresponding differences in mean or plasticity of seedling growth and allocational traits. In general, we suggest that relationships between rarity and species traits are both context and taxon specific.
Please use this identifier to cite or link to this item: | <urn:uuid:53955f2d-9aba-4581-ab72-1a1a5c5c3e7d> | 2.765625 | 401 | Academic Writing | Science & Tech. | -0.756752 | 95,507,384 |
Thousands of bulging methane bubbles could explode in Siberia
July 7, 2017, 1:04 p.m. by Michael d'Estries
Scientists estimate more than 7,000 dangerous methane 'bumps' have formed in the region over the last couple of years.
Former New Jersey landfill is a haven for migratory birds (with one fatal feature)
May 1, 2017, 10 a.m. by Matt Hickman
Officials scramble to make a methane-burning flame more bird-friendly without extinguishing it.
What are megaslumps, and how do they threaten our planet?
March 2, 2017, 9:56 a.m. by Bryan Nelson
So-called 'gateways to the underworld' opening up across the Arctic are an ominous consequence of global warming.
Probes map methane of the Four Corners
April 10, 2015, 10:18 a.m. by Stephanie Pappas, LiveScience
Scientists aren't sure where the methane is coming from, but they suspect it's related to mining.
What does methane mean for life on Mars?
December 17, 2014, 9:55 a.m. by Miriam Kramer, SPACE.com
Scientists have seen fluctuations in methane levels in the Martian atmosphere before, so any new findings add to a better understanding for the Red Planet.
Methane munching microbes live in deep-sea rocks
October 16, 2014, 10:48 a.m. by Stephanie Pappas, LiveScience
Researchers only took samples the first few inches of rock, so they aren't sure how deep the microbial communities penetrate below the surface.
Biggest U.S. methane source spotted from space
October 10, 2014, 11:10 a.m. by Becky Oskin, LiveScience
The gassy hotspot is centered over New Mexico's San Juan Basin, where some 40,000 wells suck out natural gas trapped in coal seams.
Hundreds of methane plumes erupting in Atlantic
August 25, 2014, 10:36 a.m. by Becky Oskin, LiveScience
Researchers were surprised to find so many methane seeps and can't say for sure why there are so many along the Atlantic coastline.
'Everlasting storm' has 1 million lightning strikes a year
July 23, 2014, 3:42 p.m. by Russell McLendon
The Catatumbo Lightning has helped sailors, thwarted invasions and wowed onlookers for thousands of years.
Methane-spewing microbes may have contributed to Earth's biggest extinction
April 1, 2014, 10:30 a.m. by Tia Ghose, LiveScience
Volcanic eruptions caused a massive loss of plant and animal life, but abundance of methane caused a carbon dioxide overdose that deprived surviving organisms of much-needed oxygen.
Dogs really can smell your emotional state
Injured stray dog's sweet nature wins him a bike ride — and an awesome new life
How to identify different types of bees
What's that sound? 7 wildlife calls you might hear in your backyard
9 of the world's largest dog breeds
Winning Kennel Club images celebrate dogs from all walks of life | <urn:uuid:793c1425-6767-4719-b8cb-81d4c02c5763> | 2.84375 | 656 | Content Listing | Science & Tech. | 64.410194 | 95,507,386 |
The project, titled "Analogical modelling: devising of teaching animations in Geological Sciences" is unique in our country. The experiments involve constructing parallelepipeds of sand, with casual insertions of silicone or glass spheres, on a mobile and interchangeable substratum.
The whole is subjected to compression, extension or sliding with a system of mobile vertical plates with an adjustable movement speed. Deformation thickness and speed are calibrated to simulate suitably the natural phenomenon we want to model.
The modelling device installed in the laboratory allows to photograph at fixed intervals two of the faces of the parallelepiped while it becomes deformed (plant and one of the profiles), which allows to have a vision in 3D of the progressive deformation. Finite deformation geometry can be obtained at the end of the experiment with vertical cuts in the deformed parallelepiped (solidified with water), cuts recorded with a digital camera. In every experiment, an animation is generated from digital stills. From an about two-hour long experiment, a thirty-second film can be obtained.
According to teacher Ana Crespo, "with such animations, students can appreciate qualitatively how the experiments evolves, and observe the progressive deformation in the profile and/or in the plant. They can see how rocks become deformed and form mountain ranges since, by calibrating the experiments, it can be showed in some seconds what happened in million years.
Cazorla mountain range
They can compare the final results with concrete geological cuts they have studied all through the degree course, particularly those regions located to the north of Granada and in the area of Cazorla, which are very similar to those of the laboratory".
An important aspect of this Project is its application to disclosure in the medium term. Particularly, the management of the Parque de las Ciencias (Science Park) of Granada has shown interest in this type of animations to complete the Geology section in the Biosphere hall.
Antonio Marín Ruiz | alfa
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:0bafe7ae-1732-42c8-af82-e21c3c6f554f> | 3.421875 | 986 | Content Listing | Science & Tech. | 31.869289 | 95,507,402 |
Chlorocypha fabamacula Pinhey, 1961
- scientific: C. wittei sensu Pinhey, 1961 nec Fraser, 1955
- vernacular: Spotted Jewel
Type locality: Solwezi, Zambia
Male is similar to C. victoriae by, (a) Hw 20-22 mm, rarely up to 24 mm; (b) head all black or with yellowish, brown or green spots; (c) fore tibiae entirely black; (d) at least mid and hind tibiae with anterior white streaks; (e) Abd all red, sometimes gradually becoming yellow towards end; (f) S2 largely red with paired black (sub)apical markings and S3 not black laterally. However, differs by (1) not as widespread and distributed from Katanga to N Zambia; (2) posthumeral pale stripe usually prominent rather than reduced; (3) apical markings S2 not distinctly curved laterally. [Adapted from Dijkstra & Clausnitzer 2014; this diagnosis not yet verified by author]
Mostly rivers, but also streams, shaded by gallery forest, but sometimes in open landscapes. Often with a gravelly and/or sandy bottom, dead trunks or branches, and probably submerged roots and coarse detritus. From 600 to 1500 m above sea level, but mostly between 800 and 1500.
Abdomen (dorsal view)
Map citation: Clausnitzer, V., K.-D.B. Dijkstra, R. Koch, J.-P. Boudot, W.R.T. Darwall, J. Kipping, B. Samraoui, M.J. Samways, J.P. Simaika & F. Suhling, 2012. Focus on African Freshwaters: hotspots of dragonfly diversity and conservation concern. Frontiers in Ecology and the Environment 10: 129-134.
- Pinhey, E.C.G. (1961). Dragonflies (Odonata) of Central Africa. Occasional Papers Rhodes-Livingstone Museum, 14, 1-97. [PDF file]
Citation: Dijkstra, K.-D.B (editor). African Dragonflies and Damselflies Online. http://addo.adu.org.za/ [2018-07-18]. | <urn:uuid:65b1a975-da54-497b-b3da-005d420e8f74> | 3.359375 | 495 | Knowledge Article | Science & Tech. | 70.572592 | 95,507,440 |
Solving a riddle of the sea, scientists are reporting today that the eerie thickets of snakelike creatures and towering chimneys of rich minerals that inhabit the sunless depths can form on the ocean floor not in eons, centuries or decades but as little as two or three years.
The rates of growth in some cases appear to be among the fastest known anywhere. The surprisingly swift action took place at hot vents in the ocean floor that sometimes form atop volcanic fissures.
"These findings dramatically alter our views of the rates at which biological and geological processes are occurring in a variety of environments on earth, particularly in the deep sea," said Dr. Robert Corell of the National Science Foundation, which financed the research.
"It's very important," he said in an interview, adding that the finding was "one of the most dramatic underwater discoveries in history."
The work is being reported today in the journal Nature, and was described by Rutgers University, whose scientists led the research team.Continue reading the main story
Experts said the new discoveries might one day have repercussions for the feasibility of deep-sea mining since the chimneys are known to be laced with metallic ores rich in zinc, cobalt, mercury, copper, silver and gold.
More generally, the findings are seen as important for understanding the nature of the deep hot vents, which were discovered in 1977 and have mesmerized scientists even though their great depth in the sea makes them difficult to study.
"All the time frames are much faster than we expected," said Dr. Michael Perfit, a geologist at the University of Florida in Gainesville, who has investigated the vents. "It's happening over a year or two. A lot of big things down there are forming awfully fast."
Traditionally, the ocean abyss has been thought of as a slow-motion world where all development is frustrated by low temperatures, perpetual darkness and pressures so great as to defy comprehension.
The discoveries of quick growth were by a team of researchers who studied a Pacific Ocean site for three years. The site is 500 miles southwest of Acapulco and due west of Costa Rica.
Repeatedly diving nearly a mile and a half in the submersible Alvin to study an area swept by a volcanic eruption in 1991, the scientists were surprised to find that giant tube worms could rapidly colonize a barren area and grow to lengths of nearly five feet, thriving in thickets, gently swaying like snakes in the water.
The tube worms have no eyes, no mouths, and no obvious means of locomotion or ingestion, living in symbiosis with bacteria that metabolize compounds in the water, particularly hydrogen sulfide.
Despite that, tube worms appear to be the fastest-growing of all marine invertebrates, the scientists report. That means they grow faster than clams, lobsters, jelly fish, marine worms, squids, octopuses, cuttlefishes, sea pens, sea stars, comb jellies, corals and mussels.
So, too, mineral chimneys were found to grow extraordinarily fast, quickly reaching heights of up to 34 feet. Chimneys are usually made of metals known as polymetallic sulfides. Such blends are one of the most common mineral deposits on land, typically including iron, copper, zinc and sometimes commercially significant amounts of silver and gold. Since only a tiny fraction of the area where chimneys are found, the midocean ridge that runs some 40,000 miles around the globe, it is not known how many there are.
"Taken together, the animal life and mineral formations we found are evidence that dramatically alter our views of the rates at which both biological and geological processes are occurring on the planet," said Dr. Richard A. Lutz, a Rutgers marine biologist who led the expedition. "These are more rapid than any of us in the field had envisioned."
He continued: "We found that the formation of mineral deposits is happening in time scales of years rather than eons. Biologically, these findings indicate that the giant tube worm is probably the fastest-growing invertebrate organism on earth."
In addition to Dr. Lutz, the research was conducted by Dr. Timothy M. Shank of Rutgers, Dr. Daniel J. Fornari of the Woods Hole Oceanographic Institution on Cape Cod, Dr. Rachel M. Haymon of the University of California at Santa Barbara, Dr. Marvin D. Lilley of the University of Washington, Dr. Karen L. Von Damm of the University of New Hampshire and Dr. Daniel Desbruyeres of a French ocean research institute, Ifremer.
A news conference on the work is scheduled for today at Rutgers in New Brunswick.Continue reading the main story | <urn:uuid:03d6c635-ddd0-45bc-ad7a-42b43963f162> | 3.609375 | 970 | Truncated | Science & Tech. | 44.704365 | 95,507,458 |
What happens when galaxies collide?
File photo: This beautiful new composite image of two colliding galaxies was released by NASA’s Great Observatories. The collision between the Antennae galaxies, which are located about 62 million light-years from Earth, began more than 100 million years ago and is still occurring. (NASA, ESA, SAO, CXC, JPL-Caltech, and STScI)
Paul Sutter is an astrophysicist at The Ohio State University and the chief scientist at COSI Science Center . Sutter is also host of Ask a Spaceman , RealSpace , and COSI Science Now . Sutter contributed this article to Space.com’s Expert Voices: Op-Ed & Insights .
Two galaxies are drawn together by forces they can’t see but they can feel. It’s a mutual gravitational attraction. It’s inevitable: Inch by inch, light-year by light-year, as the cosmic clock ticks on through the eons, the galaxies grow closer.
They can’t help it; their motion was set by tiny instabilities billions of years ago that have only grown stronger in the eons since. As they near each other, the galaxies begin to embrace as thin tendrils of gas and stars reaching out through the tenuous medium between them.
Then, they collide. These two massive structures, each 100,000 light-years across, host hundreds of billions of stars. During the merger, 100 trillion suns’ worth of material collide, mix and ignite. [When Galaxies Collide: Photos of Great Galactic Crashes]
And what’s left after the fireworks? A broken, dim, dying galaxy — one that will never shine as brightly or as fully as it could in the era before the great disaster.
It’s a tragic dance, a story told over hundreds of millions of years. And it’s one that we only recently began to understand.
The first simulation
As soon as astronomers realized that there are objects that are separate from our own Milky Way, they observed some galaxies that appeared to be much messier than normal. But it wasn’t immediately obvious that galaxies actually do anything as interesting as merge.
After all, this fantastic physical process takes hundreds of millions of years to play out, so the few short decades that we’ve been observing them simply isn’t enough time to watch the drama unfold in real time. For quite a while, astronomers didn’t know if galaxies were actively merging or if a fraction of galaxies just looked all weird and gangly and that’s the way the universe worked.
Simulations ultimately unraveled the mystery of tangled galaxies. But surprisingly, it was not digital simulations that did so; these simulations didn’t use a computer.
The year was 1941, and proto-computational-scientist Erik Holmberg wanted to examine the behavior of merging clusters of stars. But he couldn’t just manufacture a bunch of stars in the lab and watch them interact gravitationally over millions of years.
So Holmberg got clever. To represent a galaxy, he arranged a couple dozen lamps. Each lamp stood in for trillions of solar masses of stars, gas, dust and other assorted members of the galactic milieu. Then, he related the brightness of each lamp to the gravitational attraction of that galaxy chunk; the more massive the chunk, the brighter the lamp.
Holmberg proceeded to measure the total amount of light falling on each lamp from all of the others. This was proportional to the gravitational force from the other parts of the galaxy. This trick worked because both light and gravity follow the same inverse-square relationship: If the distance from a source doubles, both the strength of gravity and the intensity of light drop to a quarter of the original. Holmberg could then rearrange each lamp step-by-step based on the measured "gravitational pull" of the surrounding lamps.
A tale of tidal tails
In this very crude and simplistic way, Holmberg could step through the eons, watching the interplay of two galaxies as they mixed and mingled via gravity. And he saw an interesting feature: An "arm" of stars reached out between the galaxies as they drew near, with a "counterarm" appearing on the opposite side of each galaxy. While the results were intriguing, he didn’t have the computational horsepower to investigate further.
It wasn’t until the 1970s that two brothers, Alar and Juri Toomre, revisited the issue. Using actual computers to simulate the behavior of merging galaxies, they found the smoking gun: When two galaxies merge, the gravitational interactions raise "tidal tails" of gas and stars — long, thin ropes of material flung outward from the tight embrace of the spiral arms over the course of the merger event. These simulated tails looked almost exactly like pictures of intriguing objects such as the Antennae galaxies.
The picture was clear: Galaxies merge, collide and mingle. And when they do, they get ripped apart.
The force of gravity is enough to distort the shapes of galaxies as they encounter one another. But galaxies themselves are mostly (relatively) empty space. Stars are just tiny little dots compared to the enormous volumes of space within a galaxy. When you think of these beasts colliding, don’t imagine a car crash. Instead, think of two swarms of bees mixing together.
But even though the stars will generally miss each other, there can still be fireworks. Galaxies contain untold tons of gas and dust that are floating around, doing no harm, living uneventfully as nebulas.
Those nebulas can persist for ages, but if given a kick — say, from a nearby supernova shock wave or, in a more relevant example, the complex gravitational interactions as two galaxies fly through each other — they can start to collapse in on themselves, fragmenting and condensing to form a new batch of stars.
When two galaxies are merging, the star formation rate ramps up to 10 times its normal pace. In a cosmic flash, billions of new stars are born. For a brief moment, astronomically speaking, the merged galaxy will be brighter than ever before.
But all that dazzle comes at a cost. If left alone, the galaxies could keep on quietly churning out new stars year after year, sipping on their precious gaseous reserves. But the chaos of the collision forces them to use up precious supplies too quickly. Billions of new stars are born, most of them massive, only to die off shortly after the merger.
And the final result of these mergers? Grand design spiral patterns ripped to shreds. Simple flat disk tangled into a misshapen lump. A vibrant mix of old and young stars burned up with only the faint embers — dying, cool, red dwarfs — left.
Irregular galaxies, full of nothing but dim, red stars, are the leftovers of these great cosmic collisions. It’s the price paid for a moment of intergalactic glory.
Learn more by listening to the episode "What happens when galaxies collide?" on the Ask A Spaceman podcast, available on iTunes and on the web at http://www.askaspaceman.com . Thanks to Jamal and Danny N. for the questions that led to this piece! Ask your own question on Twitter using #AskASpaceman or by following Paul @PaulMattSutter and facebook.com/PaulMattSutter .
Follow us @Spacedotcom , Facebook and Google+ . Original article on Space.com . | <urn:uuid:dbf05b28-3e75-45bc-a147-b753a39f86d3> | 3.9375 | 1,579 | Nonfiction Writing | Science & Tech. | 52.477085 | 95,507,473 |
Box scores tell you how a baseball team has done. Stock listings tell you how a stock has performed. But I've never seen a mechanism indicating whether weathermen have any idea what they're talking about. Does anyone keep track of how accurate they are? --Steven Goldberg, via e-mail
Is there any evidence that computer tracking has improved the accuracy of weather forecasting? Despite the introduction of cutting-edge technologies, the weather people seem to get it wrong as much as ever. --Tom Simpson, via e-mail
Now, Tom, be fair. Weather forecasting is one of those things, like hairpieces and housework, that attract notice only when there's a problem. I'm guessing you've never had a coworker turn to you and gush, "They said the high would be 78 yesterday, and you know what it was? Seventy-eight! Man, that National Weather Service is something else!"
As you'd imagine, advances in weather prediction closely follow advances in technology and communications. Early forecasters had to make their best guesses using only basic gear (thermometer, barometer, etc) and personal experience with local conditions. In 1743 Benjamin Franklin (who else?) compiled reports from colonial postmasters to track a hurricane's progress up the eastern seaboard. By 1848 weather dispatches were traveling via telegraph, and in 1871 the newly founded U.S. Weather Bureau started publishing the first general forecasts three times a day. Weather balloons carrying radiosondes went up in the 1930s, providing a look at doings in the upper atmosphere. Finally, mathematical weather-system models, first proposed in the early 1900s, came into their own circa midcentury, when (a) computers got powerful enough to handle the calculations needed to simulate atmospheric movement and (b) radar and weather satellites greatly increased the available data.
And as computer models get updated (to include things like ocean and land effects and chaos theory) and more weather stations get sampled, forecasts do, in fact, get better. According to the American Meteorological Society, sea-level pressure forecast accuracy doubled between 1977 and 1987, and by 1991 a five-day weather forecast was as good as a three-day forecast from 1981. One study of extended forecasts from 1997 to 2004 found that using a new projection system improved temperature predictions by as much as half a degree Fahrenheit, while four-day rain forecasts improved by as much as 8 percent.
One key function of meteorology is predicting violent weather, particularly thunderstorms that could produce hail, flooding, or tornadoes, and here too there have been real advances. From 1973 to 1996 the chance of predicting a severe storm increased from 30 percent to 66 percent; between '78 and '96 the odds of a serious tornado being anticipated by a watch announcement rose from 48 percent to 95 percent. In '91 the average tornado lead time was six minutes; by 2004, thanks to NEXRAD Doppler radar, it was up to 13. Between 1990 and 2006 the National Hurricane Center greatly bettered its path projections for tropical cyclones in the Atlantic--for one-day forecasts the average tracking error dropped from about 124 miles to about 58, and from over 350 miles to less than 175 for three-day forecasts. (Interestingly, though, over the same period predictions of the storms' intensity didn't improve at all.)
Of course, forecasting's a lot easier when the weather doesn't change much. In 2005 ForecastWatch.com studied online temperature forecasts for 689 U.S. cities and found, unsurprisingly, that they were most reliable in the south and the southwest, on the west coast, and in Hawaii. Frankly, if you can't predict the weather in Honolulu, where the high's in the 80s and the low's around 70 nearly all year, you should look up "anterograde amnesia" right now, before you forget. Conversely, temperatures were hardest to foresee in the Great Plains and the northeast, where the range of possibilities is much greater. Likewise, winter forecasts are far less reliable than summer ones.
Science, however, continues to make headway. Infrared satellite scans have recently increased six-day forecast accuracy by 4 percent; the new high-resolution Weather Research and Forecasting model can reportedly cut errors in nighttime temperature and humidity prediction in half and can also help planes avoid turbulence.
Now: is anyone keeping tabs on how specific forecasters do? Sure. The aforementioned ForecastWatch compares projections by major national forecast providers and makes zip-code-specific rankings available free online. (Founder Eric Floehr won't say whether one provider is superior overall, claiming his findings can't fairly be boiled down that far.) A Phoenix firm called WeatheRate goes further: claiming to be the nation's only independent verification service for TV weather forecasts, it reviews four-day projections from local stations in about 75 cities year-round and determines a leader in each market. I don't know if that pile of underexploited stats is giving you any ideas, Steve, but let's just say that when millions of meteorology fans start fielding lineups of weathermen in your online Fantasy Weather Forecast League, I'll expect to see a cut of the sign-up fees.
Art accompanying story in printed newspaper (not available in this archive): illustration by Slug Signorino. | <urn:uuid:dc25fe68-57e1-4132-a5b6-a94f4676ce45> | 2.8125 | 1,095 | Nonfiction Writing | Science & Tech. | 42.792772 | 95,507,485 |
Nitrogen is essential to marine life and cycles throughout the ocean in a delicately balanced system. Living organisms--especially marine plants called phytoplankton--require nitrogen in processes such as photosynthesis. In turn, phytoplankton growth takes up carbon dioxide from the atmosphere and helps regulate global climate.
According to new research by Thomas Weber, an assistant professor of Earth and environmental sciences at the University of Rochester, small microenvironments in the deep ocean may hold key clues to the global cycling of nitrogen in seawater.
There are three regions in the ocean with exceptionally low oxygen levels; two off the coast of the Americas, just north and south of the equator (numbers 1 and 2) and one in the Arabian Sea (number 3). These areas are known as "dead zones" because only anaerobic microbes can survive here.
Credit: Thomas Weber / University of Rochester
In the nitrogen cycle, phytoplankton and other marine plants turn nitrate (NO3) into organic nitrogen during photosynthesis. The organic nitrogen sinks into the deep ocean, where microbes "eat" the organic nitrogen and use oxygen to respire and turn the nitrogen into nitrate. Ocean currents cycle the nitrate back to the surface ocean and nitrogen is neither lost nor gained (left panel). When oxygen runs out however, some organisms respire using nitrate instead of oxygen, converting the nitrate back into nitrogen gas, driving it into the atmosphere and removing it from the oceans.
Credit: University of Rochester illustration / Michael Osadciw
In a paper published in Nature Geoscience, Weber and his co-author Daniele Bianchi, an assistant professor of atmospheric and oceanic sciences at UCLA, show that small microbes that remove nitrogen from the water exist in these microenvironments and are more widespread than previously thought. Using this data, they developed a computer model that changes the way we think about the marine nitrogen cycle.
"The previous understanding of the nitrogen cycle was that nitrogen was lost from the ocean only in three regions where oxygen is scarce. If we wanted to predict how the nitrogen cycle would respond to climate change, all we needed to do was predict how these three low oxygen regions would expand or contract," Weber says. "Our study changes that picture by showing that nitrogen loss is actually happening over much larger regions, and we need to think about how the ocean as a whole is changing."
Most marine organisms "breathe," or respire, using oxygen. When oxygen is not present in seawater, microbes instead respire using other compounds like nitrate, a form of nitrogen. "This has the net effect of removing the nitrogen from the ocean," Weber says.
Researchers previously believed anaerobic microbes--small microorganisms and bacteria that do not need oxygen to respire--were only found in pockets of the ocean with exceptionally low oxygen levels; particularly, three regions known as "dead zones."
Weber and Bianchi have developed a computer model that takes into account new genetic data gathered from ocean microbes. The data indicates that anaerobic microbes exist not only in areas of unoxygenated water, but somehow thrive in areas of the ocean where there is oxygen. Nitrogen, therefore, may be lost across much of the ocean, not just in areas where oxygen is scarce.
"One of the biggest revolutions in oceanography in recent years has been the genomic revolution," Weber says. "Oceanographers have been able to measure all of the genes present in seawater." One of their discoveries was that the genes allowing anaerobic respiration are not just found in the three regions; the genes have been found much more widespread throughout the ocean.
Whenever oxygen is available, there should not be organisms that respire anaerobically, Weber says. "They should be outcompeted by things that use oxygen, because that's a much more efficient way to respire."
How then, do these anaerobic organisms survive in areas where oxygen is present?
Weber and Bianchi found that small "microenvironments" depleted of oxygen exist all over the deep ocean in organic-rich "marine snow"--particles of organic matter, such as dead plankton cells and zooplankton feces, stuck together. Microbes gain energy by eating the organic matter and using oxygen to respire. If the respiration is intense enough inside the particles, all the oxygen can run out and the microbes will switch to respire using compounds besides oxygen.
"We suggest that anaerobic microbes may thrive in vast swaths of the oxygenated ocean, within sinking organic 'marine snow,'" Bianchi says. "This changes the way we think of the nitrogen cycle and, more generally, anaerobic metabolism in the ocean, and suggests that both could respond to climate change in ways that challenge our current understanding."
Global warming causes ocean temperatures to rise, resulting in an increased loss of oxygen, which can then affect the nitrogen budget across the globe. When humans perturb one part of the system, it can have unexpected effects. But computer models can help better predict these consequences.
"Ocean warming is occurring because of human carbon dioxide emissions, which warm the earth as a whole," Weber says. "Indirectly, this alters the oxygen and nitrogen content of the ocean. Eventually marine phytoplankton growth and their ability to take up carbon dioxide is impacted, which then feeds back on climate change. Our new work and other modeling efforts will help us better plan for these consequences."
Lindsey Valich | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
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Calculations indicate that each human cell contains roughly a billion protein molecules. In other words, it's crowded inside the cell, and order must be maintained. What's more, newly generated proteins often need to be transported from the place they were produced to the place they are to perform their tasks.
These proteins have a kind of address label, a signal sequence, that specifies what place inside or outside the cell they need to be transported to. This transport must function flawlessly if order is to be maintained in the cell, but also for the cell to be able to communicate with its surroundings. If a protein winds up in the wrong place, it can lead to serious disorders like cystic fibrosis.
The capacity to transport proteins in most cases is directly linked to the function of the SRP, the signal-recognizing particle. The SRP binds to the signal sequence and guides it and the attached protein to the cell membrane. A key question for these researchers has been how the interaction between the signal sequence and SRP works in detail.
The Umeå scientists have managed to create a detailed picture of the first step in this protein transport by studying a complex of a signal sequence that is bound to the SRP. The technology they used is called x-ray crystallography. The group has shown the basic structure of the SRP in several previous studies SRP. Thanks to these studies, they were now able to directly compare the SRP structure with and without the guiding signal sequence.
”The structural changes were considerably greater than what was previously predicted. They provide us with detailed explanations of what role SRPs play in protein transport. These structural specifications can also serve as a model of how SRPs function at various levels during protein transport," explains Elisabeth Sauer-Eriksson, professor at the Department of Chemistry.
Now these researchers are moving on to try to investigate the next transport mechanism. For instance, they want to answer questions about what prompts the bound signal sequence to let go of the SRP and how the signal sequence, and the protein it is attached to, can make its way through the membrane.
The scientists who carried out the study are part of Umeå University's strong research environment "biological chemistry" and the Umeå Centre for Microbial Research, UCMR. Funding for the research project is provided by the Swedish Research Council, UCMR, and the Kempe Foundations.About SRP
Original title: Structural basis of signal-sequence recognition by the signal recognition particle
Authors: Tobias Hainzl, Shenghua Huang, Gitte Meriläinen, Kristoffer Brännström, and Elisabeth Sauer-ErikssonFor further information, please contact:
Karin Wikman | idw
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
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When RNA replicates itself, it tends to make perfectly complementary copies that stick together like the jaws of a zipper. Once an RNA molecule has found its complementary match, it tends not to split off and make more copies. Joyce says his goal was to create an RNA molecule that was just unstable enough to keep replicating.
For almost a decade, his team played with different combinations of the four RNA nucleotides–A, U, G, C–to create an RNA that would replicate indefinitely. Nothing kept dividing. But finally, Joyce’s team hit on the idea of creating an RNA molecule that would replicate by copying and assembling whole chunks of molecule at a time rather than working letter by letter. They engineered two such RNA molecules, called E and E-prime, and dropped them into a solution with four strands of nucleotides, precursors that might have been available on the young Earth. Within an hour, the number of RNAs had doubled, and the molecules kept replicating until all the other nucleotides in the solution had been used up, the researchers report. The replicated RNAs aren’t perfect copies, and Joyce’s team has shown that some of these mutants can outcompete their parent RNAs, becoming more populous over time. Despite being simple–the RNAs are just 70 nucleotides long–they demonstrate primitive evolution, Joyce points out.
Although the work almost certainly doesn’t reflect what happened at the start of life, it models how self-replication and mutation might have arisen–a significant accomplishment, says Andy Ellington, a molecular biologist at the University of Texas, Austin.
About the author
Rachel Zelkowitz is a science writer in Washington, D.C. | <urn:uuid:2411135e-856f-4bd8-b211-023554ce1e4d> | 4.375 | 357 | News Article | Science & Tech. | 39.94489 | 95,507,512 |
Six new species of Chinese Dragon Millipedes, including species that live exclusively in caves (Fig. 1), were recently described through international cooperation of research institutes from China, Russia and Germany. These cave species have unusually long legs and antennae, in one case resembling a stick insect (but with many more legs, Fig. 2), others appear ghosty white and are translucent (Fig. 3). The study was published in the open access journal ZooKeys.
In many tropical countries, there are numerous millipede species still awaiting discovery and description. Millipedes from China are especially little-known. Six particularly unusual species of so-called 'Dragon Millipedes', four of which found exclusively in caves, were recently discovered in southern China by an international team of researchers.
The extremely long legs of the Stick Insect Dragon Millipede, Desmoxytes phasmoides give the animal an unusual appearance, similar to a stick insect.
Sunbin Huang & Xinhui Wang (South China Agricultural University)
The team included Miss Liu Weixin from the South China Agricultural University of Guangzhou, China [LINK1], currently conducting research for her PhD focusing on Chinese cave millipedes at the Centre of Taxonomy at the Research Museum Koenig (ZFMK), Leibniz Institute for Animal Biodiversity in Bonn, Germany [LINK2], her advisor Prof. Tian Mingyi [LINK3] and a renowned millipede expert, Dr. Sergei Golovatch, from the Russian Academy of Sciences, Moscow.
Dragon Millipedes, a genus of millipedes living in SE Asia, characterized by being armoured with unusual spine-like projections as well as toxic hydrogen cyanide, have become particularly famous since the 2007 discovery and description of the "Shocking Pink Dragon Millipede" in Thailand [LINK4].
This discovery highlighted a large number of unknown millipede species [LINK4] in the Mekong region [LINK5] and worldwide [LINK6]. While the newly described cave Dragon Millipedes from China lack the 'shocking' warning colour of their surface-living relatives, they are no less spectacular.
One of the species was named the 'Stick Insect Dragon Millipede' because it features extremely long legs and antennae, and resembles a stick insect, but with many more legs (Fig. 2). Two of the other species from caves fully lost their colour, which is a common characteristic of cave-living animals.
Because of this, they appear ghostly white (Fig. 3). All the newly described species come from the two southern Chinese regions of Guangdong and Guangxi Zhuang, which host a large number of spectacular caves (Fig. 1). These caves are only now being explored in some detail.
In the course of her PhD, Miss Liu Weixin has already explored more than 200 Chinese caves (Fig. 1) and discovered and described over 20 new millipede species. The Dragon Millipedes are among her most spectacular discoveries as they exhibit extreme cave adaptations including the loss of pigmentation and extremely elongated legs and antennae. During her guest research year at the Research Museum Koenig in Bonn, Germany, Liu is currently busy describing more than two dozen further millipede species, which she collected from Chinese caves – literally bringing to light an unknown world.
Contact person(s): Sergei Golovatch [English], 7(499)936-7671,
firstname.lastname@example.org; Thomas Wesener [German], 0049 (0)228 9122-425, email@example.com
Publication: Six new species of dragon millipedes, genus Desmoxytes Chamberlin, 1923, mostly from caves in China (Diplopoda, Polydesmida, Paradoxosomatidae). Weixin Liu, Sergei Golovatch, Mingyi Tian
ZooKeys 577: 1-24 (05 Apr 2016)
Zoological Research Museum Alexander Koenig – Leibniz-Institute for Animal Biodiversity (ZFMK) is an independent research institute. The focus of research is on performing an inventory of the zoological species diversity on earth, on the analysis of changes in biodiversity as a result of environmental factors, and on evolutionary processes at the morphological and molecular levels. ZFMK furthermore explores the context of structure and function of ecological systems, advanced scientific methods, and the study of the history of science. The permanent exhibition “Our blue planet – the living network” offers a genuine nature experience based on naturalistic ecosystem displays.
The Leibniz Association is a network of 89 scientifically, legally, and economically independent research institutes and scientific service facilities. Leibniz Institutes perform strategic and thematically-oriented research and offer scientific service of national significance while striving to find scientific solutions for major social challenges.
Sabine Heine | idw - Informationsdienst Wissenschaft
Abrupt cloud clearing events over southeast Atlantic Ocean are new piece in climate puzzle
23.07.2018 | University of Kansas
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
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Back action (quantum)
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(Quantum) back action refers (in the regime of Quantum systems) to the effect of a detector on the measurement itself, as if the detector is not just making the measurement but also affecting the measured or observed system under a perturbing effect. Back action has important consequences on the measurement process and is a significant factor in measurements near the quantum limit, such as measurements approaching the Standard Quantum Limit (SQL).
Back action is an actively sought-after area of interest in present times. There have been experiments in recent times, with nanomechanical systems, where back action was evaded in making measurements, such as in.
- Braginsky, V .B.; Khalili, F. Ya. (1992). Quantum Measurement. Cambridge University Press. ISBN 978-0521484138
- Hartridge, M. et al., Quantum Back-Action of an Individual Variable-Strength Measurement, Science 339, 178 (2013), https://science.sciencemag.org/content/339/6116/178
- Hertzberg, J. B. et al., arXiv/0906.0967, https://arxiv.org/ftp/arxiv/papers/0906/0906.0967.pdf
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|This quantum mechanics-related article is a stub. You can help Wikipedia by expanding it.| | <urn:uuid:1d7f14e6-23f6-4fd1-9a7a-739b625b8abf> | 2.625 | 347 | Knowledge Article | Science & Tech. | 57.141481 | 95,507,540 |
In a breakthrough experiment using a novel negative ion momentum imaging technique, researchers from Tata Institute of Fundamental Research, Mumbai India and Open University, Milton Kyenes, UK have shown -- for the first time -- that incoherent electrons displaying their quantum mechanical nature, can induce coherence in molecular systems on attachment.
Their latest results published in the Journal, Nature Physics (DOI: 10.1038/nphys4289), show that the coherence induced by the capture of single electron by H2 molecule results in the ejection of H? ion in preferentially backward direction with respect to the incoming electron beam.
Momentum images of H from H2 and D from D2 at different electron energies. The one at 4 eV for H is symmetric, while those above 14 eV are strongly asymmetric. The asymmetry in D is less pronounced and appear to change direction with change in electron energy.
Credit: E. Krishnakumar et al, Nature Physics
The other product of the dissociation is the H-atom in its excited state. In other words, this coherence induced in the molecule segregates the charge and excess energy in the system in a preferred manner. Similar measurements in the isotopomer of H2 namely D2 does not show such a strong asymmetry in ejection of the fragment ion but shows the reversal of the asymmetry as a function of incoming electron energy.
So far researchers have used such coherence induced by laser beams to control molecular dissociation and have considered it as the basis for possible control of chemical reactions using photons. But in that case, the coherence in the resulting excited molecular entity is understood to stem from the absorbed laser radiation. By demonstrating the presence of such coherence resulting from a capture of an incoherent electron, Prof. Krishnakumar and co-workers have shown that such coherence can also stem from the transfer of more than one value of angular momentum quanta.
On the capture of a low energy electron, a relatively unstable molecular negative ion is formed. Subsequently, this negative ion decays by ejecting the extra electron. However, if the ion survives against the electron ejection, it undergoes dissociation.
This is known as dissociative attachment. According to Prof. Krishnakumar, dissociative attachment is traditionally linked with transfer of multiple values of angular momentum quanta in the molecular system. However, it is for the first time such a quantum coherent response has been observed from a molecule.
Low energy electrons are ubiquitous and are known to play important role in variety of phenomena relevant to astrochemistry (where they participate in synthesis of new molecules), in radiation biology (where they cause chemical changes in living cell, plasma chemistry), atmospheric chemistry, radioactive waste management and nanolithography -- to name but a few.
In all these cases, dissociative attachment plays a critical role. The unstable excited molecular negative ion states are at the core of this process. However, due to very short lifetime of these species very little is known about them at present.
The group led by Prof. Krishnakumar and Dr. Prabhudesai in TIFR has pioneered research on several aspects of low energy electron interactions with molecules in gas and condensed phase with particular emphasis on the possibility of controlling chemical reactions using low energy electrons.
These new results point to rich unexplored dynamics of excited molecular negative ions that might open up new possibilities in inducing chemical control. They also pose a challenge to theoreticians to come up with a detailed model for the negative ion chemistry that is associated with low energy free electron scattering.
These measurements were carried out by Prof. Krishnakumar using an experiment built by him at the Open University in UK, where he was on invitation as a Marie Curie Professor to help build a novel electron scattering experiment for the European scientists, similar to the one he had conceived and built at TIFR. Dr. Prabhudesai and Prof. Krishnakumar provided the interpretation of the data along with the model.
E. Krishnakumar | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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12 July 2018
Fiddling with metal atoms
Published online 9 November 2016
Scientists invent a technique that allows them to fine tune the properties of silver atoms.
Organic ions or molecules that bind to the surface of noble metal nanoclusters are known as ligands. Usually, these ligands are modified to allow for tailoring the nanoclusters leading to potential practical applications.
So far, however, it has not been well understood how modifying the ligand alters the electronic and optical properties of the metal nanoclusters.
In a new study published in Inorganic Chemistry1, scientists from Saudi Arabia and the US demonstrate how surface-bound mercaptonitrobenzoic acid molecules can alter the electronic and optical properties of silver nanoclusters.
They were able to induce such change by tweaking the pH chemistry of such systems.
At pH levels higher than 13, the surface-bound organic acids lose hydrogen ions, in turn forming soluble and stable silver nanoclusters in aqueous solutions.
When pH was lowered from 13 to 7, two adjacent acid molecules on the surface of the nanoclusters formed chemical structures called dimers, each one consisting of two identical molecules of the acids.
These dimers are responsible for changing the electronic structure of the nanoclusters as well as their optical properties.
“This research offers a simple and efficient tool for tuning optical and electronic properties of metal nanoclusters which are potentially useful for making photo-active catalysts and biomedical sensors,” says lead scientist Omar Mohammed from the King Abdullah University of Science and Technology (KAUST), Saudi Arabia.
- AbdulHalim, L. G. et al. pH-induced surface modification of atomically precise silver nanoclusters: an approach for tunable optical and electronic properties. Inorg. Chem. 55, 11522–11528 (2016). | <urn:uuid:a408bd2a-b23a-4e66-ab7c-01df6a518e13> | 3.25 | 380 | Truncated | Science & Tech. | 27.564496 | 95,507,569 |
English | 2014 | ISBN: 0321940520, 9780321940520 | 305 Pages | True PDF | 4.54 MB
HTML and CSS can be a little daunting at first but fear not.
This book, based on Shay Howe's popular workshop covers the basics and breaks down the barrier to entry, showing readers how they can start using HTML and CSS through practical techniques today. They'll find accompanying code examples online, while they explore topics such as the different structures of HTML and CSS, and common terms. After establishing a basic understanding of HTML and CSS a deeper dive is taken into the box model and how to work with floats.
The book includes an exercise focused on cleaning up a web page by improving the user interface and design, solely using HTML and CSS. With a few quick changes the web page changes shape and comes to life. Interactive, technically up-to-the-minute and easy-to-understand, this book will advance a student's skills to a professional level. | <urn:uuid:be77755d-917c-4098-92c1-76d0b642188a> | 2.65625 | 205 | Product Page | Software Dev. | 63.358807 | 95,507,608 |
+44 1803 865913
Illustrations by GE and JC Rotheray
Aphids and their colonies are excellent arenas in which to observe predators in action. A range of insects come to eat or parasitise the aphids or to drink their honeydew. Other books in the series deal with the natural history of two major groups of aphid predator, Hoverflies, and Ladybirds. This book complements them by focussing on the behavioural interactions among these and other visitors to a colony.
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We all need to help promote 350.org.
Their mission is not simple one– Inspire the world to rise to the challenge of the climate crisis–to create a new sense of urgency and of possibility for our planet!
350 parts per million CO2 🙁
If we can’t get below that, scientists say, the damage we’re already seeing from global warming will continue and accelerate. But 350 is more than a number–it’s a symbol of where we need to head as a planet.
Scientists say that 350 parts per million CO2 in the atmosphere is the safe limit for humanity. Learn more about 350 – what it means, where it came from, and how to get there. Visit 350.org TODAY!!
The Solar Impulse is relying on sun power as it rides around the clock and attempts night flight.
The Solar Impulse, an experimental solar plane, took off on a historic ride around the world early today from Geneva, Switzerland. Supporters hope that this flight will prove the value of solar energy.
According to team co-founder Bertrand Piccard, a record-breaking balloonist who’s father and grandfather, the prototype has been designed to test and promote new energy-efficient technologies.
“The goal of the project is to have a solar-powered plane flying day and night without fuel,” Piccard said. “This flight is crucial for the credibility of the project.”
Ten test flights have been completed since the project began seven months ago. The prototype aircraft is a single-seater shaped like a giant dragonfly. It has 12,000 solar panels spread across its 207 foot (63 meter) wingspan. The aircraft is powered by four small electric motors and will depend on the sun to charge its batteries.
The theory is that the aircraft will store enough energy during the day to last through the night. Pilot Andre Borschberg, a former flight jet pilot, will attempt to stay alert during the flight with the help of a ground control team that is monitoring the aircraft on the teams website.
Borschberg, 57, is wearing a parachute just in case he runs into trouble in the air. | <urn:uuid:1a28dc64-4d58-4ba9-853c-9dea5f5378e4> | 3.359375 | 454 | Content Listing | Science & Tech. | 63.191053 | 95,507,651 |
How Deep Learning Gives Us a Precise Picture of All the Water on Earth
Water levels can indicate the next region that will experience political unrest or where climate change is hitting the hardest. Orbital Insight is monitoring them by applying deep learning to satellite images.
Where exactly is all the water on Earth’s surface? Stand-alone satellite images have their limitations, but using artificial intelligence to examine them can now glean precise levels of water around the world and how they are changing week by week.
Palo Alto startup Orbital Insight uses freely available images taken by the U.S. Geological Survey’s Landsat 7 and 8 satellites, much like the images you see on Google Maps. The startup feeds the images into a neural network, which pinpoints the exact location and area of surface water.
While it’s not a new feat to track the Earth’s water levels, Orbital Insight is approaching the task with a specially trained neural network that labels water pixel by pixel. The team manually sorted through thousands of images to find examples with clearly and accurately marked water, and then trained the neural network with them.
“We basically built ... Tinder for Landsat maps: Swipe right if it’s good, swipe left if it’s bad,” CEO James Crawford says of the system the researchers used.
As a result, the neural network is especially good at picking up on what’s water and what’s not, whereas other water-detecting systems might identify the shadows of clouds or mountains as water.
Water-level data at this depth could be of interest to many groups. Insurance companies investigating the extent of a flooding event, for instance, or agencies interested in tracking climate change and water levels over the course of the year.
Orbital Insight can now label the world’s water every two weeks. Eventually, it will drop that number down to one week.
Steven Glaser, who directs the Citris Intelligent Water Infrastructures and Adaptive Cities Initiative at the University of California, Berkeley, notes that most water models are based on the last 50 years, which may soon make them out-of-date.
“With climate change, these models are becoming moot,” Glaser says. “The more information we can gather as the climate is changing, the better we can model, and better models are needed for the water security of all users.”
Water can also tell us something about the future—droughts can lead to crop failures and displacement. Even nations can squabble over water, leading to political unrest.
“Some of that stress is exacerbated by things like water rights and how the water is shared between various countries,” says Orbital Insight engineering director Shwetank Kumar. “Once you can measure the amount of water available, who is using what, etc., then you can develop a good framework to think about water rights.”
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Selenium is a naturally occurring trace element that can become concentrated and released by industrial, agricultural, petrochemical and mining activities. At concentrated levels it is toxic and has polluted ecosystems around the world. This book will serve as a comprehensive practical handbook for everyone dealing with selenium in aquatic environments. It offers field-tested approaches and methods for assessment and water quality management. Using his twenty-year experience, the author discusses the effects of selenium on fish and bird populations and presents guidelines for identifying sources of pollution, interpreting selenium concentrations, assessing hazardous conditions, setting water quality criteria and ecosystem loading limits (TMDLs). He also includes a procedure for setting environmentally safe limits that ensure compliance with EPA regulations. Selenium Assessment in Aquatic Ecosystems will interest field scientists, natural resource managers, risk assessors and environmental planners.
This book is the outcome of a NATO Advanced Research Workshop on "The Eastern Mediterranean as a laboratory basin for the assessment of contrasting ecosystems" that was held in Kiev, Ukraine, March 23-27, 1998. The scientific rationale of the workshop can be summarized as follows. The Eastern Mediterranean is the most nutrient impoverished and oligotrophic large water body known. There is a well-defined eastward trend in nutrient ratios over the entire Mediterranean that starts at the Gibraltar Straits and, through the western basin, proceeds to the Ionian and Levantine Seas. Supply of nutrients to the entire Mediterranean is limited by inputs from the North Atlantic and various river systems along the sea. The unique feature of the Mediterranean is the presence of an eastward longitudinal trend in available nitrate/phosphate ratios. This apparently induces a west-to-east variation in the structure of the pelagic food web and trophic interactions. In this context the Mediterranean, and in particular its Eastern basin, provides probably a unique platform to explore the hypotheses related to the suggested phosphate-limitation on production and to the shift between "microbial" and "classical" modes of operation of the photic food web. The major exception of the overall oligotrophic nature of the Eastern Mediterranean is the highly eutrophic system of the Northern Adriatic Sea. Here, during the last two decades the discharges of the northern rivers (especially of the Po), together with municipal sewage, have led to a very marked increase of nutrients and subsequent imponent eutrophication events.
This book focuses on fluxes of energy, carbon dioxide and matter in and above a Central European spruce forest. The transition from a forest affected by acid rain into a heterogeneous forest occurred as a result of wind throw, bark beetles and climate change. Scientific results obtained over the last 20 years at the FLUXNET site DE-Bay (Waldstein-Weidenbrunnen) are shown together with methods developed at the site, including the application of footprint models for data-quality analysis, the coupling between the trunk space and the atmosphere, the importance of the Damkohler number for trace gas studies, and the turbulent conditions at a forest edge. In addition to the many experimental studies, the book also applies model studies such as higher-order closure models, Large-Eddy Simulations, and runoff models for the catchment and compares them with the experimental data. Moreover, by highlighting processes in the atmosphere it offers insights into the functioning of the ecosystem as a whole. It is of interest to ecologists, micrometeorologists and ecosystem modelers.
Deepwater Horizon Articles
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Washington: Many well-known comets such as Halley and Hale-Bopp originally formed in other solar systems, according to a Queen`s University researcher.
The study, by Queen`s University astronomy professor Martin Duncan and an international team of astronomers, appears in the online journal Science Express.
Prof Duncan said: "Anyone who has seen a long tail comet in the night sky may be looking at material from another star," says Professor.
The researchers used computer simulations to show that the Sun may have captured small icy bodies from its sibling stars while it was in its birth star cluster, and this created a reservoir for observed comets.
Although the Sun currently has no companion stars, it is believed to have formed in a cluster containing hundreds of closely packed stars that were embedded in a dense cloud of gas.
During this time, each star formed a large number of small icy bodies (comets) in a disk from which planets formed.
Most of these comets were gravitationally slung out of these prenatal planetary systems by the newly forming giant planets, becoming tiny, free-floating members of the cluster.
The Sun`s cluster came to an end when its gas was blown out by the hottest young stars.
The researchers` computer models show that the Sun then gravitationally captured a large cloud of comets as the cluster dispersed.
Prof Duncan said: "The process of capture is surprisingly efficient and leads to the exciting possibility that the cloud contains a potpourri which samples material from a large number of stellar siblings of the Sun."
Evidence for the team`s scenario comes from the roughly spherical cloud of comets (called the Oort cloud) which surrounds the Sun.
Exactly how the Oort cloud was created has been a mystery for more than 60 years.
Prof Duncan added: "We have a new model of how the Oort cloud formed. We`re not the first to suggest this could happen but we are the first to show it in a detailed computer simulation." | <urn:uuid:609ad4e1-fa27-4e2b-9354-d7c7b7cbf4be> | 3.71875 | 411 | News Article | Science & Tech. | 45.837515 | 95,507,673 |
Radioactivity: An Introduction to Mysterious Science
Received Date: Aug 08, 2017 / Accepted Date: Sep 03, 2017 / Published Date: Sep 08, 2017
Materials that undergo decay process to attain a stable configuration followed by the emission of particles such as alpha, beta and gamma are termed as radioactive elements. Radioactivity is measured in Curie (Ci) and Becquerel (Bq) SI units. Though radioactive elements are abundant on Earth and constantly decays to produce stable nuclei but such nuclear decay process may pose serious health threats to living beings. Therefore, must be regulated when working in vitro. Biosafety levels should be strictly observed when engaged in radioactive experiments to minimize contamination exposure.
Keywords: Radioactive decay; Radioactive poisoning; Alpha particles; Beta particles; Half-life
In 1896 Henri Becquerel discovered phenomena of radioactivity by exposing potassium uranyl sulfate to sunlight, considering that it will emit neutral X-rays but in actual the emitted radiation was electrically charged since it bent in the magnetic field. So, the experiment was conducted using different elements that emits radiation that showed deflection in different directions in the magnetic field or not at all. Thus three different types of radioactive radiations i.e., negative, positive, and neutral were identified . Marie Curie coined the term radioactivity and along with her husband Pierre, discovered other radioactive elements such as radium and polonium from radioactive ore of uranium for which she won a second Nobel Prize in 1911. Becquerel and the Curies received the Nobel Prize in 1903. The next important step down this road of discovery came from Ernest Rutherford who characterized the defining properties of these radioactive particles and named these as alpha, beta, and gamma particles. Classification of these radiations was based on their ability to penetrate matter. Alpha particles being massive moves slowly as compared to beta and gamma particles [2-4].
Radioactivity in nature
Elements with atomic number (Z) higher than Bi is radioactive in nature and are abundant in Earth. The earth also contains several elemental radioisotopes such as Potassium-40 which undergoes beta decays to form stable 40 Ar and 40 Ca. Uranium to lead ration revealed that Earth is approximately 4.5 billion years old. Rn 222, an intermediate product of U238 decay with 3.8 days half-life contributes in background radiation. Radioactive isotopes such as 7 Be and 14 C are constantly produced in the upper atmosphere. In order to gain understanding of Earth structural construct, study of radioactivity is crucial [5,6].
Becquerel (Bq) after Henri Becquerel is the unit in which radioactivity is measured and which the number of decays per second is.
One day per second equals one Becquerel
Curie another unit, named after Pierre and Marie Curie.
One curie is the activity of 1 gram of radium and equals 3.7 × 1010 Becquerel.
SI units and prefixes
|Radioactivity||Absorbed Dose||Dose Equivalent||Exposure|
|Common Units||curie (Ci)||Rad||Rem||roentgen (R)|
|SI Units||becquerel (Bq)||gray (Gy)||sievert (Sv)||coulomb/kilogram (C/kg)|
Table 1: SI Units for measuring radioactivity.
|To convert from||To||Multiply by|
|Curies (Ci)||Becquerels (Bq)||3.7 × 1010|
|millicuries (mCi)||megabecquerels (MBq)||37|
|microcuries (µCi)||megabecquerels (MBq)||0.037|
|millirads (mrad)||milligrays (mGy)||0.01|
|millirems (mrem)||microsieverts (µSv)||10|
|milliroentgens (mR)||microcoulombs/kilogram (µC/kg)||0.258|
|Becquerels (Bq)||Curies (Ci)||2.7 × 10-11|
|megabecquerels (MBq)||millicuries (mCi)||0.027|
|megabecquerels (MBq)||microcuries (µCi)||27|
|milligrays (mGy)||millirads (mrad)||100|
|microsieverts (µSv)||millrems (mrem)||0.1|
|microcoulombs/kilogram (µC/kg)||milliroentgens (mR)||3.88|
Table 2: Conversion Equivalence.
Radiation measurements: Different related units are used for measuring radioactivity, absorbed dose, exposure and dose equivalent (r-e-a-d).
• Curie (Ci) and Becquerel (Bq) are the units for the measurements of radioactivity which refers to the concentration of emitted particles by a sample. It denotes the number of atoms in the given sample that decayed in a given time period.
• Coulomb/kilogram (C/kg) and Roentgen (R) are the units for exposure which is defined as the amount of radiation traveling through the air.
• Gray (Gy) and radiation absorbed dose (rad) measures the concentration of absorbed (deposited) radiation by a material or person.
• Sievert (Sv) and Roentgen equivalent man (rem) are units to measures dose equivalent also known as effective dose which is defined as the amount of absorbed radiation and its medical effects. Dose equivalent is same as the absorbed dose for beta and gamma radiation but larger than the absorbed dose for alpha and neutron radiation that are more damaging .
Types of radiations: Ionizing radiation emitted during radioactive decay are categorized as alpha, beta, gamma, protons, and neutrons.
Radioactive decay: Around 50 naturally occurring radioisotopes are found on earth. Impulsive radioactive fragmentation of an atomic nucleus to achieve a stable form by the emission of radiations is termed as radioactive decay . Based on different types of radiations released during decay process there are three types of radioactive decays which are as follows:
Alpha particle (4He nucleus) is emitted during the decay process. Such nuclei have high proton to neutron ratio. Alpha particles are quiet stable in their configuration with two protons and two neutrons. Protons to neutrons ratio is reduced in the parent nucleus after decay by altering the Z. so the parent and the daughter atoms are chemically different elements .
Beta particles are negatively charged electrons or positively charges electrons (positron) that is emitted from nuclei with too many protons during decay. There are two types of beta decays.
1) Beta minus decay: In which a neutron decays into a proton, an electron, and an antineutrino
2) Beta plus decay: In which a proton decays into a neutron, a positron, and a neutrino .
Through the emission of photons in gamma decay, the atomic mass of the parent and daughter nucleus remains the same. Thus parent and daughter atoms are chemically similar elements .
Half life: Half-life is defined as the time taken for one-half of the nuclei in a sample to decay. It is denoted by t1/2. Radioactive decay is as an exponential process. N denotes the number of original nuclei remaining after a time t from an original sample of N0 nuclei.
Properties of radioactive radiations
Alpha particles: Alpha particle contains two neutrons and two protons
• Particle carry positive charge.
• Mass of each alpha-particle is 4 times that of a proton or H-atom.
• Ionization power of alpha rays is very high.
• Penetration power of is very small
• Produce fluorescence in different substances
• Produce burn and source on human body
• Produce artificial radioactivity is certain nuclei
• They have strong ionizing power because they remove electrons from the atoms of gas through which they pass
• Their velocity range is 3 × 107 m/s to 3 × 106 m/s.
• Highly energetic emits 5 MeV.
• Travel only a few centimeters in air and is easily stopped by a paper sheer or the outer skin layer. Radon, uranium, radium, and thorium are alpha emitters..
• Negatively charged particles i.e., Electron
• Velocity is from 9 × 107 m/sec to 27 × 107 m/sec
• Affect the photo graphic plate
• Ionization power is very small
• Kinetic energy is less than that of alpha - rays.
• Produce fluorescence in different substance
• Produce secondary radiations called bremsstrahlung
• Travel several meters in air and millimeters into the human body and is stopped by an aluminum or plastic sheet. Sulfur-35, hydrogen-3 phosphorus-33, phosphorus-32 and carbon-14 are beta emitters.
• Electrically neutral
• Travel with the velocity of light that is 3 × 108 m/sec
• Penetration power is very large. It is about hundred times larger than that of alpha rays.
• Produce feeble fluorescence
• Travel at the speed of light
Numerous incidents in the past revealed that if biosafety levels are not strictly observed when working with radioactive isotopes, it increases the possibility of contamination with life threatening consequences. For example in 2006 murder of former Russian intelligence and death of Marie Curie’s daughter Irene by radioactive polonium. Similarly in 2003 a Russia journalist, Yuri Shchekochikhin and in 2004 a St Petersburg businessman Romam Tsepov died of radioactive poisoning . Therefore it is important to keep in mind the safety considerations and measures while working in lab to ensure a radioactive free environment is established for protection of an individual from radioactive poisoning.
Following safety levels should be observed while working with a radioactive material:
Defensive clothing: When working with an open radioactive source wear long length gloves and lab coats, closed toe shoes, safety glasses/goggles, radiation dosimeter, radiation monitor badges etc., to cover maximum parts of your body to avoid radioactive exposure because radioactive incidents frequently involves spills or splashes which can readily contaminate bare parts of the body.
Drinking/Eating: Drinking/eating, smoking etc., should be avoided where open radioactive sources present or stored to reduce the possibility of radioactive content intake in the body.
Oral pipetting: Mouth pipetting of radioactive solutions must not be avoided.
Security: Radioactive resources should be placed in shielded storage containers with proper labelling at secured places with maximum supervision and should not be left in an unattended lab or room.
Radioactive warning labels: Proper signs and symbols should be used to indicate the presence or storage of radioactive materials to avoid mishandling and exposure [24,25]. Labeling of rooms and containers of radioisotopes is mandatory under the following conditions [26,27] (Table 4).
|Radioactive isotopes||Activity (uCi)|
Table 4: Radioisotope activity labelling.
Hoods and biosafety cabinets: Volatile radioelements i-125 or S-35 methionine/cysteine, must be handled inside specifically designed RAM hoods or safety cabinets equipped with alarming flow monitoring device to eliminate the risk of contamination.
ALARA: Radiation exposure must be kept as low as reasonably achievable means all safety measures and monitoring should be attempted to keep radiation doses ALARA .
Lab working concerns
• Be aware with the relative properties of the radioactive isotope that is to be used with any specific precautionary concerns specific to that radioisotope.
• Unexperienced nuclear procedures should be rehearsed before engaging with the actual radioactive substance following standard biosafety levels such as protective clothing, use of contamination free safety hoods, etc.
• Avoid direct handling of radioactive entities instead use remote handling tools and instruments.
• Proper storage of radioactive waste in specifically designed labelled storage cans with substantial Plexiglas shielding from external radiation levels.
• Authorized access to individuals to radioactive storage facilities with maximum security and supervision to avoid unauthorized access or breaching.
• Biosafety rules and regulations for working with radioisotopes should be made visible for everyone before the start of an experiment.
• Proper storage/disposal of radioactive waste in shielded cans and containers.
• Contamination monitoring should be done on regular basis after every nuclear experiment conducted.
Thus, radioisotopes are an abundant source of radioactive emissions that can be used in different biomedical applications but needs strict biosafety regulation to avoid exposure.
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- Browne E, Dairiki JM, Doebler RE (1978)Table of isotopes. National Standard Reference Data System.
- Houtermans H, Milosevic O, Reichel F (1980) Half-lives of 35 radionuclides.The Intern J App Rad Isot31: 153-154.
- Woods MJ, Collins SM, Woods SA (2004)Evaluation of half-life data. National Physical Laboratory.
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- Bahr B, Lemmer B, Piccolo R (2016) Alpha, Beta and Gamma Rays. In: Quirky Quarks, Springer Berlin Heidelberg, pp: 170-173.
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Citation: Khan NT (2017) Radioactivity: An Introduction to Mysterious Sciencey. J Phys Chem Biophys 7: 254. Doi: 10.4172/2161-0398.1000254
Copyright: © 2017 Khan NT. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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The electromagnetic spectrum is radiation found in day to life as discussed unit 10 classroom tutorial, capable traveling vacuum. Most common type of light unlike mechanical waves. Spectroscopy and spectroscopic Dr haarp weather control. Rakhesh Singh Kshetrimayum 7 is project secret weapon used achieve weather control more? history channel cbc documentaries show grave dangers of. Transmission line analysis 1 Electromagnetic Field Theory by R s p e c t r a from jim kaler s stars. S we know what stars made of, their structures lives, only because we able observe analyze. Chapter 8 waves David Morin, [email protected] gravitational collision do give an enormous amount new information about collision. Harvard mostly comes after.
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Continental margins are shallow water regions of the ocean where a variety of methane sources are found. A supersaturation of methane in oceanic surface waters has been widely observed, but the source responsible for this supersaturation, which results in the sea-to-air flux of methane, can be variable over space and time. Determining the dominant source of methane to continental margin surface waters is the central focus of my graduate research. Radiocarbon methane measurements from surface waters will be my primary tool, but stable methane isotope measurements from the water column will also be made in order to tell a more complete story of the methane dynamics at work.
- 2012-2017, Ph.D. Graduate Student, Dept of Earth & Environmental Sciences, University of Rochester, Rochester, NY.
- 2011-2012, Ph.D. Graduate Student, Dept of Oceanography, Texas A&M University, College Station, TX.
- 2011, B.S., Environmental Science, University of North Carolina at Wilmington, Wilmington, NC.
- K. J. Sparrow, J. D. Kessler, J. R. Southon, F. Garcia-Tigreros, K. M. Schreiner, C. D. Ruppel, J. B. Miller, S. J. Lehman, X. Xu, Limited contribution of ancient methane to surface waters of the U.S. Beaufort Sea shelf. Science Advances 4, eaao4842 (2018).
- K. J. Sparrow and J. D. Kessler (2017) "Efficient collection and preparation of methane from low concentration waters for natural abundance radiocarbon analysis." Limnology & Oceanography: Methods, doi: 10.1002/lom3.10184.
- Garcia-Tigreros Kodovska, F., K.J. Sparrow, S.A. Yvon-Lewis, A. Paytan, N.T. Dimova, A. Lecher, J.D. Kessler. (2016) “Dissolved methane and carbon dioxide fluxes in Subarctic and Arctic regions: Assessing measurement techniques and spatial gradients.” Earth and Planetary Science Letters, doi: 10.1016/j.epsl.2015.12.002.
- Dimova, N.T., A. Paytan, J.D. Kessler, K.J. Sparrow, F. Garcia-Tigreros Kodovska, A.L. Lecher, J. Murray, and S.M. Tulaczyk. (2015) "Current Magnitude and Mechanisms of Groundwater Discharge in the Arctic: Case Study from Alaska." Environmental Science & Technology, doi: 10.1021/acs.est.5b02215.
- Lecher, A.L., J.D. Kessler, K. Sparrow, F. Garcia-Tigreros Kodovska, N. Dimova, J. Murray, S. Tulaczyk, A. Paytan. (2015) “Methane transport through submarine groundwater discharge to the North Pacific and Arctic Ocean at two Alaskan sites.” Limnology and Oceanography, doi: 10.1002/lno.10118.
- Paytan, A., A. Lecher, N. Dimova, K. Sparrow, F. Garcia-Tigreros Kodovska, J.D. Kessler. (2015) “Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study.” Proceedings of the National Academy of Sciences, doi:10.1073/pnas.1417392112.
- 2015, Sparrow, K. and J. Kessler. Efficient Collection and Preparation of Methane from Extremely Large Volumes of Water for Natural Radiocarbon Analysis. 22nd International Radiocarbon Conference, Dakar, Sénégal. (Talk)
- 2014, Sparrow, K. and J. Kessler. Efficient Collection of Methane from Extremely Large Volumes of Water for Natural Radiocarbon Analysis. AGU General Meeting, San Francisco, CA. (Poster)
SHIPBOARD & FIELD EXPERIENCE
- 2015, August 28 - September 5, R/V Ukpik, Prudhoe Bay, Alaska, USA
- 2014, July 7-14, R/V Endeavor, North Atlantic Bight, USA
- 2012, August 7-14, R/V Cape Hatteras, Gulf of Mexico, USA
- 2012, July 29 - August 3, Barrow Field Station, Barrow, Alaska, USA
- 2012, July 24 - 28, Toolik Field Station, Toolik Lake, Alaska, USA
- 2012, July 19 - 23, Kasitsna Bay Laboratory, Kasitsna Bay, Alaska, USA
- 2011, August 21 - 28, Kasitsna Bay Laboratory, Kasitsna Bay, Alaska, USA
- 2011, August 13 - 20, Toolik Field Station, Toolik Lake, Alaska, USA
- 2011, August 8 - 12, R/V Ukpik, Prudhoe Bay, Alaska, USA
- Teacher’s Assistant, Spring 2013, Stable Isotope Geochemistry: Fractionation Equations and Models (EES 261/461)
- Environmental Education Intern, Summer 2010, Chincoteague Bay Field Station of the Marine Science Consortium, Wallops Island, Virginia
- 2013 March, Girls in Ocean Science High School Teen Conference, Ocean Institute, Dana Point, California - I introduced high school girls to chemical oceanography with dissolved oxygen profiling experiments during a day cruise aboard the Ocean Institute’s research vessel.
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WAVE CHARACTERISTIC OF PARTICLES (SIFAT GELOMBANG DARI PARTIKEL)
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In the Year 1923, while still a graduate student of University Of Paris, Louis de Broglie published a brief article in the journal Comptes Rendus containing revolutionor ideas to the understanding of physics at the most fundamental level, namely: “That the Wave Nature of Particles Having Intrinsic“.
Werner Heisenberg and Erwin Schrödinger developed a theory based on the wave nature of particles. In 1927, Davisson and Germer confirmed the wave properties of particles with diffraksi electrons from a single crystal of nickel. | <urn:uuid:84e84a7d-14fa-402a-97be-6b478a3ab8c7> | 2.9375 | 173 | Product Page | Science & Tech. | 4.14 | 95,507,742 |
Global warming set to breach 2C limit by 2050, scientists warn
The Pasterze glacier (in photo) is Austria's largest and is shrinking rapidly, having receded in length by at least three kilometers since the 19th century. Photograph: (Getty)
Global warming is on track to breach a 2 degrees Celsius (3.6 degrees Fahrenheit) threshold by 2050 unless governments double their efforts to limit greenhouse gas emissions, seven of the world's top scientists warned on Thursday.
"Climate change is happening now, and much faster than anticipated," Sir Robert Watson, former head of the UN's Intergovernmental Panel for Climate Change (IPCC), the body charged with distilling climate science for policy makers, was quoted as saying by AFP news agency.
Due to climate change, devastating weather-related events including floods, drought, more intense storms, heat waves and wildfires, have doubled in number since 1990, a report put together by the seven scientists states says, the international news agency reports.
"Without additional efforts by all major emitters (of greenhouse gases), the 2C target could be reached even sooner," Watson said during a teleconference.
“The INDC’s (Intended Nationally Determined Contributions is a term used under the United Nations Framework Convention on Climate Change for reductions in greenhouse gas emissions) are totally inadequate to meet the 2-degree Celsius goal,” he was quoted as saying in the media reports.
“Governments must double and redouble their pledges,” he said, adding that it’s almost certain that the average global temperature will surpass the aspirational 1.5 degree goal as soon as 2030.
The report, prepared on behalf the Universal Ecological Fund, an Argentine-based NGO and was co-authored by scientists from Austria, Argentina, Brazil, Italy, the United Kingdom and the US, also says that pledges made under the Paris climate agreement are inadequate.
Inked by 195 nations in December, the Paris Agreement set an even more ambitious target, vowing to cap warming at "well under" 2C, and even 1.5C if possible. The deal may enter into force by the end of year.
"I think the 1.5 degree pathway is clearly not achievable. We'll pass it probably in the early 2030s," Watson observed adding there is a dire need to cut down the greenhouse gas emissions.
The co-authors of the report include Carlo Carraro, scientific director of the Fondazione Eni Enrico Mattei in Italy, and vice-chair of one of three IPCC working groups, Nebojsa Nakicenovic, deputy director of the International Institute for Applied Systems Analysis in Vienna and lead author the IPCC working group III.
2015 was the hottest year on record, and 2016 is shaping up to be even warmer, US and European government scientists have forecast, according to AFP.
Global warming is projected to cause more heatwaves, droughts, downpours and rising sea levels, Reuters observes.
Average world temperatures this year are set for record highs, about 1C above pre-industrial times.
(WION with inputs from AFP, Reuters) | <urn:uuid:c3f49880-9fbe-4a6a-bbcd-035eee11848c> | 2.84375 | 651 | News Article | Science & Tech. | 37.011251 | 95,507,765 |
Water – colorless, odorless and tasteless – may seem simple, but its interaction with minerals can be difficult to study. Ions (ranging from nutrients such as calcium, to contaminants such as lead) are present in natural waters, but their transport is often limited by adsorption to mineral surfaces. The more scientists can understand about the interaction of minerals with water and ions, the more effectively they can control water quality in our environment, and Argonne's research in this area is making a leading contribution to the field.
Contrary to generally held scientific assumptions, the simple textbook description of how ions adsorb to mineral-water interfaces has been shown to not be universally true. Argonne Physicist Paul Fenter stated "Ions are known to carry a hydration shell in water. Previously, it was thought that ions either adsorb to a mineral surface with this shell intact as an outer-sphere ion, or remove part of this shell to directly bind to the mineral as an inner-sphere ion. We now know that this is not just a black and white difference, but have discovered new shades of gray by showing that outer-sphere and inner-sphere species of the same ion can co-exist."
This revelation was the outcome of a new element-specific method developed to understand the behavior of ions at the interface between minerals and liquids, like water. According to Argonne Chemist Changyong Park, "Conventional methods provided no direct sensitivity to observing this behavior. Outer-sphere species were almost invisible and extremely difficult to identify. There was just no way to see the co-existence of both species previously."
Using the Advanced Photon Source (APS) at Argonne, which provides the western hemisphere's most brilliant x-ray beams for research, the team was able to make this new discovery. These x-rays enabled scientists to pursue new knowledge about the structure and function of materials – and develop new methods for scientific study. Using the APS, the team was able to take advantage of the technique's spectroscopic sensitivity to identify the way specific ions interact at mineral-water interfaces and visualize the phenomena directly.
The findings built on earlier work on cation adsorption using traditional x-ray scattering techniques. The Argonne scientists, working together with researchers from the University of Illinois at Chicago Department of Earth and Environmental Sciences, previously discovered an anomaly in the way that ions adsorb. The team collaborated again with the new element-specific technique which led to this new discovery, central to understanding the behavior of ions at solid-liquid interfaces.
Water is the "universal solvent", dissolving more substances than any other liquid. This means that wherever water goes, either through the ground or through our bodies, it takes ions along with it. A general understanding of this behavior and the development of a new scientific method for studying this phenomenon may lead to better understanding of various other processes that take place at solid-liquid interfaces, including corrosion, erosion, catalysis, and even the biological behavior of cell membranes.
Eleanor Taylor | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
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Accumulation - the process in which water pools in large bodies (like oceans, seas and lakes).
Condensation - the process in which water vapor (a gas) in the air turns into liquid water. Condensing water forms clouds in the sky. Water drops that form on the outside of a glass of icy water are condensed water. (This term appears twice in the diagram.)
Evaporation - the process in which liquid water becomes water vapor (a gas). Water vaporizes from the surfaces of oceans and lakes, from the surface of the land, and from melts in snow fields.
Precipitation - the process in which water (in the form of rain, snow, sleet, or hail) falls from clouds in the sky.
Subsurface Runoff - rain, snow melt, or other water that flows in underground streams, drains, or sewers.
Surface Runoff - rain, snow melt, or other water that flows in surface streams, rivers, or canals.
Transpiration - the process in which some water within plants evaporates into the atmosphere. Water is first absorbed by the plant's roots, then later exits by evaporating through pores in the plant. | <urn:uuid:14ae4370-0dd9-4d26-8700-e4f8fdde53da> | 3.390625 | 327 | Structured Data | Science & Tech. | 47.93175 | 95,507,810 |
Move the ends of the lines at points B and D around the circle and find the relationship between the length of the line segments PA, PB, PC, and PD. The length of each of the line segments is. . . .
In the middle ages stone masons used a ruler and compasses method to construct exact octagons in a given square window. Open your compasses to a radius of half the diagonal of the square. . . .
If I print this page which shape will require the more yellow ink?
Three equilateral triangles ABC, AYX and XZB are drawn with the point X a moveable point on AB. The points P, Q and R are the centres of the three triangles. What can you say about triangle PQR?
Triangle ABC has equilateral triangles drawn on its edges. Points P, Q and R are the centres of the equilateral triangles. What can you prove about the triangle PQR?
When a strip has vertical symmetry there always seems to be a second place where a mirror line could go. Perhaps you can find a design that has only one mirror line across it. Or, if you thought that. . . .
A design is repeated endlessly along a line - rather like a stream of paper coming off a roll. Make a strip that matches itself after rotation, or after reflection
The shortest path between any two points on a snooker table is the straight line between them but what if the ball must bounce off one wall, or 2 walls, or 3 walls?
I noticed this about streamers that have rotation symmetry : if there was one centre of rotation there always seems to be a second centre that also worked. Can you find a design that has only. . . .
Show that for any triangle it is always possible to construct 3 touching circles with centres at the vertices. Is it possible to construct touching circles centred at the vertices of any polygon?
The points P, Q, R and S are the midpoints of the edges of a convex quadrilateral. What do you notice about the quadrilateral PQRS as the convex quadrilateral changes?
A and B are two fixed points on a circle and RS is a variable diamater. What is the locus of the intersection P of AR and BS?
Four rods are hinged at their ends to form a convex quadrilateral. Investigate the different shapes that the quadrilateral can take. Be patient this problem may be slow to load.
Medieval stonemasons used a method to construct octagons using ruler and compasses... Is the octagon regular? Proof please.
A circle has centre O and angle POR = angle QOR. Construct tangents at P and Q meeting at T. Draw a circle with diameter OT. Do P and Q lie inside, or on, or outside this circle?
Keep constructing triangles in the incircle of the previous triangle. What happens?
We use statistics to give ourselves an informed view on a subject of interest. This problem explores how to scale countries on a map to represent characteristics other than land area.
The points P, Q, R and S are the midpoints of the edges of a non-convex quadrilateral.What do you notice about the quadrilateral PQRS and its area?
In the diagram the radius length is 10 units, OP is 8 units and OQ is 6 units. If the distance PQ is 5 units what is the distance P'Q' ?
Two perpendicular lines lie across each other and the end points are joined to form a quadrilateral. Eight ratios are defined, three are given but five need to be found.
In the diagram the point P can move to different places around the dotted circle. Each position P takes will fix a corresponding position for P'. As P moves around on that circle what will P' do?
In the diagram the point P' can move to different places along the dotted line. Each position P' takes will fix a corresponding position for P. If P' moves along a straight line what does P do ?
The diagonals of a trapezium divide it into four parts. Can you create a trapezium where three of those parts are equal in area? | <urn:uuid:3e8d2afc-4093-4e52-8a9d-3e1d0d82349d> | 3.546875 | 885 | Content Listing | Science & Tech. | 71.905502 | 95,507,813 |
Probability, Random Variables and Random Signal Principles P. Peebles
The addition of independent random We can mention control theory, signal processing, chemical physics, anomalous diffusion, and many other areas, where FC revealed superior results than classical calculus [25–36]. Therefore, the pgf of a fair coin is . Probability and random variables and random signal principles. Probability and random process peyton z.peebles. Another sleeper theorem is Jensen's inequality: If φ is a convex function and X is a random variable, φ( E(X) ) ≤ E( φ(X) ). Let us recall that for a discrete random variable , taking values , the probability generating function (pgf) is defined as , where is the probability mass function of . Besides, in those systems, there is always the existence of various types of random signals, such as noise (temperature impact of electronic components), interference (random effects of other signals in the environment of communication), the transmission and receiving of random information (such as For probability and statistics, the subject includes: the probabilistic model, the basic concepts of probability theory, random variables, multiple random variables, and random processes. Probability, Random Variables, and Random Signal Principles By Peyton Z. I remember being unsettled by this theorem when I took my first probability course. Probability, Random variables and stochastic processes - A. Http://www.filefactory.com/file/cbefa06/n/peebles_solution.rar. Complex Analysis – when complex numbers were discovered in the 16th century, their applied use case scenarios were beyond the comprehension of the time: electromagnetism, signal analysis, fluid dynamics, relativity, The Pigeon Hole Principle maybe? | <urn:uuid:42a3c2f3-dc7c-47ff-8b75-58bdc225d7b4> | 3.28125 | 369 | Spam / Ads | Science & Tech. | 23.801989 | 95,507,855 |
Isotopes participate in the same chemical reactions but often at differing rates.
When isotopes are to be designated specifically, the chemical symbol is expanded to identify the mass (for example, C is not stable.
However, human beings love to see factual precision, and we want to know how old something is.
Please remember that all dating methods, even those termed "absolute," are subject to margins of error. That is a very small amount of possible error range. Modern studies almost always use two or more methods to confirm dating work and to build confidence in the results obtained.
For example, based on the primate fossil record, scientists know that living primates evolved from fossil primates and that this evolutionary history took tens of millions of years.
By comparing fossils of different primate species, scientists can examine how features changed and how primates evolved through time.
As a result it is always undergoing natural radioactive decay while the abundances of the other isotopes are unchanged.
The 6 proton 6 neutron atoms are said to have a mass of 12 and are referred to as "carbon-12." The nuclei of the remaining one percent of carbon atoms contain not six but either seven or eight neutrons in addition to the standard six protons.
Carbon-14 reacts identically to Carbon-12 and is rapidly oxidised to form (Carbon-14)Dioxide.
Since all living organisms on Earth are made up of organic molecules that contain Carbon atoms derived from the atmosphere, they therefore contain Carbon-14 atoms.
Dating is not necessary to demonstrate that evolution is a fact.
Chronological sequence is all that is really required. | <urn:uuid:76059cd4-cd7b-4122-aea6-777518e8d44a> | 4.1875 | 337 | Knowledge Article | Science & Tech. | 35.403196 | 95,507,870 |
THIS DATASET HAS BEEN WITHDRAWN and superseded by United Kingdom Butterfly Monitoring Scheme: collated indices 2014
Collated indices are a relative measure of butterfly abundance across monitored sites in the UK, calculated from data collected by the UK Butterfly Monitoring Scheme (UKBMS). Collated indices are calculated annually for each individual butterfly species that has been recorded on five or more sites in that year. Based on this criterion collated indices have been calculated for the entire UKBMS time series from 1976 to the current year for the majority of species. For some rarer species the time series starts in a later year due to lack of data. Collated indices are calculated using a statistical model that accounts for missing data. The number of sites for each species ranges from 5 to several hundred and varies from year to year. Since 2008 more than 1,000 sites have been monitored across the UK each year. Collated indices are calculated so that we can determine how butterfly populations are changing over time across the UK. This data can be used, for example, to determine where to target conservation efforts and to measure the condition of the UK countryside. Butterflies are recognised as important indicators of biodiversity and environmental change (e.g. as official UK Biodiversity Indicators), and have been used in numerous research studies to understand the impacts of changes in climate and the extent and condition of habitats. Although the Centre for Ecology & Hydrology (CEH) and Butterfly Conservation (BC) are responsible for the calculation and interpretation of the Collated indices, the collection of the data used in their creation is ultimately reliant on a large volunteer community. The UKBMS is funded by a consortium of organisations led by the Joint Nature Conservation Committee (JNCC).
Publication date: 2014-10-07
This dataset is part of the following
Collated indices are produced using a series of statistical models on butterfly transect counts recorded by a volunteer network. These indices are a relative measure of each species' abundance across the UK compared to the baseline in 1976. The statistics are presented as log10 values. These values are centred around an arbitrary value of 2 as a mean for the time series in order to help show which years are below or above average (a technique used in other biodiversity indicators). | <urn:uuid:7c5d63eb-ca7e-4ede-a8fd-ddfd07df2e56> | 3.171875 | 465 | Knowledge Article | Science & Tech. | 24.635728 | 95,507,878 |
NASA has Tropical Storm Dolly covered by satellite and the remotely piloted Global Hawk aircraft. Both captured data on Dolly before it made landfall in eastern Mexico.
The MODIS or Moderate Resolution Imaging Spectroradiometer instrument aboard NASA's Terra satellite took an image of Tropical Storms Norbert in the Eastern Pacific and Dolly in the Gulf of Mexico at 1:30 p.m. EDT on Sept. 2. The image showed Dolly is a much more organized storm than Norbert, and revealed Dolly's strongest, towering thunderstorms around the center of circulation. Norbert is close to the western coast of Mexico, so the country has tropical storms to the east and west. The image was created by the NASA MODIS Rapid Response Team at NASA's Goddard Space Flight Center in Greenbelt, Maryland.
At 11 p.m. EDT on September 2, Dolly made landfall between Tampico and Cabo Rojo, near latitude 21.9 north and longitude 97.7 west.
One of NASA's unmanned Global Hawk aircraft number 872 surveyed Tropical Storm Dolly during the night-time hours of September 2 as part of NASA's latest hurricane airborne mission known as the Hurricane and Severe Storm Sentinel, or HS3 mission.
"We saw winds at low levels (near 850 millibars) up to about 35 to 40 knots (40 to 46 mph) and a reasonably depicted cyclonic circulation," said HS3 Principal Investigator, Dr. Scott Braun of NASA's Goddard Space Flight Center in Greenbelt, Maryland. "The data at 150 millibars (high in the atmosphere) shows the strong outflow from the storm to the east and southeast."
In the image, the dropsonde data gathered from NASA's Global Hawk were adjusted over the satellite image of the storm to compensate for the storm's movement. As a result, although the image makes dropsonde data look as if it were over eastern Mexico, there were no drops over the country. The data was just shifted to match the satellite image. All dropsondes were dropped over the Gulf of Mexico.
NASA's HS3 mission returned to NASA Wallops Flight Facility, Wallops Island, Virginia for the third year to investigate the processes that underlie hurricane formation and intensity change in the Atlantic Ocean basin. HS3 is a collaborative effort that brings together several NASA centers with federal and university partners.
By 8 a.m. EDT (1200 UTC) on September 3, Dolly had weakened to a depression with maximum sustained winds near 35 mph (55 kph). The National Hurricane Center (NHC) expects Dolly to weaken quickly and dissipate by the end of the day on September 3. Dolly was centered near latitude 21.7 north and longitude 98.8 west, about 65 miles (110 km) west-southwest of Tampico, Mexico. Dolly was moving toward the west near 8 mph (13 kph) and is expected to continue in that direction for the next day or so taking Dolly farther inland.
As with any tropical cyclone that makes landfall, heavy rainfall is always a concern. The NHC expects Dolly to produce rainfall amounts of 5 to 10 inches with isolated maximum amounts of 15 inches across much of Tamaulipas and Nuevo Leon...as well as northern Veracruz and eastern San Luis Potosi, Mexico through Wednesday evening. This rainfall is expected to cause life-threatening flash floods and mud slides in areas of mountainous terrain.
Rob Gutro | Eurek Alert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:b524e44a-d414-40ff-85ec-b72a455dfac1> | 3.3125 | 1,290 | Content Listing | Science & Tech. | 48.302335 | 95,507,892 |
dna string 88.
(photo credit: )
The Human Genome Project mapped out man's genetic makeup, but a "Human Cell Lineage Project" is still needed to map the history of the body's cells back to the fertilized egg. Now Weizmann Institute researchers have developed an analytical method to trace the lineage "trees" of cells. The method could answer numerous fundamental questions in biology and medicine, such as where do stem cells originate, how does cancer develop, and when do cell types split off from each other in the embryo.
This accomplishment started with a challenge to common wisdom, which says that every cell in an organism carries an exact duplicate of its genome. Although mistakes in copying, which are passed on to the next generation of cells as mutations, occur when cells divide, such tiny flaws are thought to be trivial. But research students Dan Frumkin and Adam Wasserstrom of the Rehovot Institute's biological chemistry department, working under the guidance of Prof. Ehud Shapiro, raised a new possibility: Though biologically insignificant, the accumulated mutations might hold a record of the history of cell divisions.
Together with Prof. Uriel Feige of the computer science and applied mathematics department and research student Shai Kaplan, they proved that these mutations can be used to trace lineage on a large scale, and then applied the theory to extracting data and drafting lineage trees for living cells. Methods used until now for charting cell lineage trees have relied on direct observation of developing embryos. This technique worked well enough for the tiny transparent worm C. elegans, that has a maximum of 1,000 cells, but for humans with 100 trillion cells, or even newborn mice or human embryos at one month, each of which has a billion cells after some 40 rounds of cell division, the task would be impossible.
The study focused on mutations in specific, mutation-prone areas of the genome known as microsatellites (genetic phrases consisting of a few nucleotides or genetic letters); mutations manifest themselves as additions or subtractions in length. Based on the current understanding of the mutation process in these segments, the scientists proved mathematically that microsatellites alone contain enough information to accurately plot the lineage tree for a one-billion-cell organism.
Both human and murine genomes contain around 1.5 million microsatellites, but the team's findings showed that a useful analysis can be performed based on a much smaller number. To obtain a consistent mutation record, the team used organisms with a rare genetic defect found in plants and animals alike. While healthy cells have repair mechanisms to correct copying mistakes and prevent mutation, cells with the defect lack this ability, allowing mutations to accumulate relatively rapidly.
Borrowing a computer algorithm used by evolutionary biologists that analyzes genetic information to place organisms on branches of the evolutionary tree, the researchers put together an automated system that samples the genetic material from a number of cells, compares it for specific mutations, applies the algorithm to assess degrees of relatedness, and from there outlines the cell lineage tree. To check their system, they pitted it against the tried-and-true method of observing cell divisions as they occur in a lab-grown culture. The team found that, from an analysis of just 50 microsatellites, they could recreate an accurate cell lineage tree.
While the research team plans to continue testing their system on more complex organisms such as mice, several scientists have already expressed interest in integrating the method into ongoing research in their fields.
THE STOMACH NEVER LIES
Instead of looking at brain waves or sweaty palms, lie detector experts may be advised to focus on the stomach instead. A new study suggests that changes in gastric physiology perform better than standard polygraph methods in distinguishing between lying and telling the truth. The University of Texas study, presented at the recent Annual Scientific Meeting of the American College of Gastroenterology, demonstrates a link between lying and a significant increase in gastric arrhythmia.
To test their hypothesis that the gastrointestinal tract is uniquely sensitive to mental stress because of the communication between the central nervous system and the enteric nervous system, University of Texas researchers recruited 16 healthy volunteers to undergo simultaneous electrogastrogram (EGG) and electrocardiogram (ECG) recordings. The researchers found that both lying and truth telling affected cardiac symptoms, while the act of lying was also associated with gastric symptoms. The EGG showed a significant decrease in the percentage of normal gastric slow waves when the subject was lying. That corresponded to a significant increase in the average heart rate.
"We concluded that the addition of the EGG to standard polygraph methods has clear value in improving the accuracy of lie detectors," said Dr. Pankaj Pasricha, the chief researcher. "The communication between the big brain and the little brain in the stomach can be complex, and merits further study," he said.
CELLPHONES & HOSPITALS GET ALONG
Improved cellular phones and medical equipment appears to have lessened the phones' interference with hospital monitors and respirators, a Mayo Clinic study indicates. Researchers there reached this conclusion after spending four years studying the interaction between the two. Many hospitals ban the use of cellphones on the premises, or restrict them to certain areas.
In their most recent analysis, Mayo Clinic researchers report in the the October issue of Mayo Clinic Proceedings that the cellphones they tested didn't interfere with medical devices more than a meter away, marking an improvement. Nearly half of the devices recorded some interference, but the vast majority of such interference should not have had any significance for the patient.
The researchers completed their study of six models: Nokia Model 5165 (digital); Sanyo Model SCP-4900 (digital); Nokia Model 3585i (digital); Motorola Model 205 (digital); Motorola V60 (digital); and Nokia Model 3585i (analog). Dr. David Hayes, head of the cardiovascular disease division at the Mayo Clinic, said that since technological changes in both cellular phones and medical equipment continue, periodic testing of the communications devices to determine their effects on medical equipment will be needed. | <urn:uuid:c28eeca7-3152-4da5-ae9d-86e01a7be322> | 3.703125 | 1,245 | News Article | Science & Tech. | 25.316752 | 95,507,893 |
Using Combined Close-Range Active and Passive- Remote Sensing Methods to Detect Sinkholes
Received Date: Dec 27, 2017 / Accepted Date: Jan 03, 2018 / Published Date: Jan 05, 2018
In the Dead Sea region of Israel, sinkholes collapse can be observed easily due to the large number of sites. The continuous decrease in Dead Sea level over the last 30 years, caused a substantial increases the sinkhole activity (more than 3,000 sinkholes upper layer collapse). Sinkholes of up to 50 m diameter are found to be clustered in sites with variable characteristics. In this research, we have developed methods for prediction of sinkholes appearance by using mapping and monitoring methods based on active and passive remote-sensing means. These methods are based on measurements from several instruments including field spectrometry, geophysical ground-penetration radar (GPR) and a frequency domain electromagnetic (FDEM) instrument. Field spectrometry was used to compare the spectral signatures of soil samples collected near progressing sinkholes and those taken in regions with no visible occurrence of sinkholes. Active remote sensing showed higher electrical conductivity and soil moisture in the former regions. Measurements were taken at different time points to monitor the progress of an "embryonic" sinkhole. The research steps included (i) review of previous published literature, (ii) mapping of regions with an abundance of sinkholes in various stages, and areas that are vulnerable to them, (iii) data analysis and development of warning indicators, accessible information to the scientific community.
The result derived from this research indicates the possibility to build a pre-warning tool to detect the formation of sinkholes.
Keywords: Sinkhole; Passive remote sensing; Active remote sensing; Spectroscopy; Frequency domain electromagnetic; Groundpenetration radar
The Dead Sea basin located in the Dead Sea Transform, is exposed to the destructive process of sinkhole collapse. A substantial increase in sinkhole activity in the last two decades has resulted from the continuous decrease in the Dead Sea's level. The near-surface layers of the Dead Sea basin consist of massive sedimentary rocks—dolomite, limestone and others at the margins, and alluvial and evaporate materials in the basin. A sinkhole is a topographic depression caused by the sudden or gradual collapse of underground rock layers. Sinkhole formation occurs in many parts of the world (e.g., Spain, United States, Italy, and Thailand) . The mechanism responsible for the appearance of sinkholes is dissolution of soluble rocks and creation of subsurface cavities [3,4] and these mechanical processes are influenced by erosion processes . The dissolved rock is usually a carbonate with a rather slow dissolution rate, or salt, with a much higher dissolution rate [7-9]. Salt outcrops are rare and produce landscapes that are typically associated with karst formations, characterized by local sinkholes, valleys and underground streams [10,11]. Evaporates vary largely in their solubility and dissolution rates. Salt (halite, NaCl), a common mineral and rock at the subsurface, is >100 times more soluble than gypsum. Salt is soluble in most aquatic environments. Therefore, the subsurface dissolution of salt and collapse of the overlying material in sinkholes may be extremely large in salty rocks. Remote-sensing approaches have been presented to monitor the processes of subsurface salt dissolution and associated sinkhole hazards along the Dead Sea coast . These methods have allowed delineating salt-layer boundaries, estimating the layer's porosity distribution, finding cavities within the layer, identifying deformations in the overlying sediments and detecting caves using multiple geophysical methods . Collapsed sinkholes started to appear along the Dead Sea coast in Israel and Jordan in the early 1980’s. Sinkhole development has significantly accelerated since 2000, with the abrupt occurrence of over 3,000 of them. This regional-scale collapse is attributed to the rapid decline of the Dead Sea level (1 m/yr) [1,13,14]. This decline, which has exceeded 40 m since the early 1930’s, reflects human activities, such as interception of the freshwater supply from the Jordan River and maintenance of large evaporation ponds by Dead Sea mineral industries in Jordan and Israel.
Based on geological and hydrological evidence [13,15], sinkholes in the Dead Sea are formed by salt-layer dissolution [13,16]. Sinkhole formation is also sometimes associated with the fault structure of the Dead Sea basin, as well as land subsidence caused by compaction of fine-grained sediments (clay and silt) in the upper part of the sedimentary fill. Some authors have associated the development of subsurface cavities to the variations in Dead Sea level over the past four decades [5,13,15]. Recent studies have related the formation of subsurface cavities to underground water flow. The cavity develops upward due to underground flow, forming a sinkhole when the collapsed level reaches the surface . The development of subsurface cavities is sometimes correlated with the presence of geotectonic faults [18,19]. To assess the presence of faults or sinkholes, a high-resolution three-dimensional (3D) seismic reflection survey was carried out between the Dead Sea shoreline and Route 90 (which runs parallel to the western shore of the Dead Sea), where sinkholes develop in the alluvial fan and lacustrine deposits. Processing of the 3D time–volume data showed sub-horizontal coherent reflectors at approximately 35-70 m depth . The authors suggested a possible link between the revealed fault and some sinkholes. Large sinkholes that are visible on the surface can reach diameters of 25 m , and several of them together can form mega-sinkholes which are hundreds of meters in length. More than 3,000 sinkholes have already developed in the Dead Sea basin that are likely related to the existence of underground cavities created by salt dissolution .
Electromagnetic (EM) methods were used by Ezersky et al. to monitor sinkholes and subsoil information. That author used a transient EM method to map the electrical resistivity of the subsurface through the Nahal Hever South area, which is characteristic of the Dead Sea coast. Those measurements allowed detailed differentiation of layers (clay, salt, etc.) in the subsurface based on their bulk resistivity. Ezersky et al. [18,19] found that sinkhole development is linked to the salt edge in the Dead Sea area.
Forward modeling results indicated that both high resistivity and residual gravity anomalies are associated with subsurface de compaction of the soil mass and deep cavities at the sinkhole site. The sinkhole was slowly moving toward the Dead Sea Ezerzky et al., [18,19]. Similar studies carried out in the Ghor Al-Haditha area (Jordan) showed that the sinkholes there are also arranged along the winding line conforming to the salt edge [18,19]. Geomorphic changes, including sinkhole development, can be extremely rapid, particularly in areas where human activity alters groundwater circulation . The sinkholes in the Dead Sea area form relatively quickly; they influence the shape of the sea coast, cause changes in the soil and water, and affect crop and vegetation status, along with damage to the infrastructure. In this study, we used active and passive remote-sensing methods (Table 1) to monitor sinkhole formation before it is complete and exposed to the surface. We further localized the forming sinkholes both temporally and spatially.
|Method||Task for which used||Frequencies/EM spectral region|
|Frequency domain Electromagnetic (FDEM)||Measuring subsurface electrical conductivity and magnetic susceptibility||625 Hz; 1,975 Hz; 6,125 Hz; 19,175 Hz; 60,025 Hz|
|Ground-penetration radar (GPR)||Imaging the subsurface for sinkhole identification||100 MHz|
|Analytical Spectral Device (ASD)||Soil mineralogy, soil moisture of near- surface soil layers||350–2500 nm|
Table 1: Characteristics of the close-range remote-sensing instruments used in this study.
Materials and Methods
Study area and sampling methods
In the first stage of the primary survey, four regions along the west coast of the Dead Sea were tested as potential research sites, based on the presence of surface subsidence, and the structural and mechanical properties of the soil and underground rock (Figure 1). Soil samples were collected from all of the plots (study areas) for laboratory analysis and spectral measurements. In the second stage, we chose the area near Ein Gedi Hot Springs for our research. Subsamples were collected at two different times. Figure 2A describes the Ein Gedi locations: "Ein Gedi South" was located about 400 m south of Ein Gedi Hot Springs, where meaningful sinkholes are visible. The plots were divided into a matrix size of 60 × 70 m, and samples were taken at 10 m intervals (Figure 2B). Each sampling point was defined using a benchmark.
The analysis involved active and passive remote-sensing methods and chemical analyses of the soil samples. An Analytical Spectral Device (ASD) field spectrometer was used, which covers the EM spectral region (350–2500 nm) and consists of 2,151 bands. The spectral sampling interval was 1.4 nm in the 350–1000 nm range, and 2 nm in the 1000–2500 nm range. The channel width (FHMW) was 3 nm in the 350–1000 nm range, and 10 nm in the 1000–2500 nm range. There were three sensors for three sensitive areas along the visible (VIS)–near infrared (NIR)–shortwave infrared (SWIR) spectral regions, with an optical fiber length of 1.4 m, and a field of view (FOV) of 25° without lenses. The instrument scans very rapidly, acquiring single spectra in milliseconds via its fiber-optic input. In recent years, there has been an increase in the use of active remote-sensing tools such as GPR (Figure 3a) and subsurface FDEM (Figure 3b) systems for measuring the subsurface EM velocity and dielectric constant (GPR), and the EC profile and magnetic susceptibility (MS) of the subsurface (FDEM).
The FDEM method provides a geophysical tool for measuring EC and MS (apparent values) of subsurface rocks, soils and minerals. The FDEM method involves generating EM fields that induce alternating subsurface eddy currents, which in turn cause the subsurface materials to form relative magnetic fields. By measuring these magnetic fields, apparent subsurface properties such as EC and MS can be deduced. EC depends on the soil and rock matrix, percent saturation, and conductivity of pore fluids. The FDEM instrument provides two measurement values simultaneously—the quadrature component which is strongly dependent on the EC, and the in-phase component, which responds strongly to MS. FDEM has distinct advantages over many other techniques . In this study, we used a Gem-2 sensor operated in multi frequency mode with the following five frequencies: 625 Hz; 1,975 Hz; 6,125 Hz; 19,175 Hz; 60,025 Hz. There is a connection between frequency and penetration depth such that the lower the frequency, the deeper the penetration. The maximum penetration depth achieved was 10–15 m and the minimum was 2-3 m. The size of the spatial resolution changed from a few centimeters up to 10 cm at 3 m depth. The first stage of data processing aimed to reduce the spikes (due to metal objects and field obstacles) and smooth the data. The smoothing operation was iterative at different levels to preserve the accuracy of the raw data. In the second stage, in-phase and quadrature values were converted into apparent MS and apparent EC, respectively. Data gridding was performed in the third stage to produce maps.
In GPR methods, EM waves serve to image the subsurface by transmitting radar pulses into the ground and receiving the signal returning from the interfaces below, to map subsurface layers and moisture content . GPR can provide continuous high-resolution profiling of subsurface features such as geological features, recent faults and more . In the last decade, numerous sedimentological studies have used GPR to reconstruct the nature of sedimentary processes [24,25]. Here, a RAMAC GPR was operated at a nominal center frequency of 100 MHz to create subsurface-profile images and to detect subsurface sinkholes, soil–rock discontinuities and variations in water content. A series of cross sections were taken at sample intervals of 0.25 m along the profiles to obtain radar-reflection images, to an average depth of about 7-10 m.
Research hypotheses and flowchart
Sinkhole formation is a complex process, with certain physical and chemical soil properties as significant components. These features can be monitored by remote sensing (passive/active) and spectroscopy. Combining these methods improves the ability to identify early stages of sinkhole development. The study was performed in three stages (Figure 4).
The first consisted of defining the tested areas. The second consisted of integrated information-gathering for simultaneous information acquisition from the different remote-sensing methods, both passive and active. These methods provided an understanding of all of the parameters that favor sinkhole formation and results were compared to references of the processed ground sections to a depth of approximately 15 m. The third stage included the production process and drawing conclusions based on data results.
Spectral soil properties of the study regions
Figure 5 shows the continuum removal of the average spectral measurements of soils from the study regions in the Dead Sea (see Figure 1 for location of spectral measurements). A comparison between samples allowed classifying the regions into two groups: (i) Mitzpe Shalem (Tmarim field) (Figure 1, group 1, northern region), and (ii) Mineral Beach, Shemurat Kane and Ein Gedi (Figure 1, group 2, southern region). This classification was based on water absorption in the 1350–1500 nm and 1750–1900 nm spectral regions. Note that the Mitzpe Shalem sample also varied at 2350 nm and 2250 nm. The northern region is characterized by sandy soil (the density and strength of the sand layers is unknown) with high permeability to water. The southern region is characterized by clayey soil with high water-adsorption capacity and low permeability. According to laboratory analyses, 40% of the soil sample from the southern region was characterized by a grain size smaller than 0.034 mm. In the northern region, only 10% of the soil sample had a grain size smaller than 0.034 mm. Soil moisture content in the northern region was lower than that in the southern region.
Analysis of EC values as an indicator of ground section sinkholes for micro-zone monitoring
The "Ein Gedi South" plot was mapped to about 15 m depth on different dates (Figure 6a and 6b) for 625 Hz: the red-purple color indicates high EC values of more than 3400 mS/m; the bluegreen color indicates relatively low EC values of less than 2400 mS/m. The northeast purple strip in Figure 6 represents an area close to a sinkhole developing on the surface. This strip is expected to spread to the southwest of the areas shown in purple and red. Figure 7 shows NE–SW EC profiles for the two measurement dates presented in Figure 6.
The "Ein Gedi South" plot was mapped and sampled on two different dates: 11 Nov 2011 and 12 Apr 2012. The mapping was conducted at five different frequencies from 625 to 60,025 Hz, at depths of between 0 and 15 m, to study the sinkhole-formation mechanism on spatial and temporal scales. A comparison of measurements from the two samplings showed expansion of the sinkhole area at the second time point, emphasized by the pink-purple color in the northeastern part of the area (Figure 6). Moreover, higher EC values were observed at the second time point. Analysis of other frequencies gave a similar picture, with the area being divided into three regions.
In the "Ein Gedi South" plot, sinkholes were observed on the surface (final stage of development) and in a highly devolved (intermediate) stage. In "Ein Gedi North", no sinkholes were observed on the surface. A low EC level was observed in the western region and a high EC level in the eastern region of both plots. Unlike the "Ein Gedi North" plot, in "Ein Gedi South", there was continuity of the EC values and the axis of progression was clearer. Moreover, a comparison of the two dates showed that in November, the western region of "Ein Gedi South” was stable, with no significant changes in EC values between the two time points (Figure 6).
Cross-sectional reflection imaging was monitored by GPR at a nominal frequency of 100 MHz to achieve good penetration resolution to an effective depth of about 10 m (Figure 8). The profiles were processed in different ways using band pass average=median, and average removal filters with different gains. The raw data (without any filter, aside from the display parameters) were presented for comparison. A vertical cross section was generated at problematic sites and the soil-profile layers were interrelated. Figure 8 presents the GPR cross sections. Two different analyses are presented for each section: the first (Figure 8a) highlights the areas of relatively high moisture near the sinkholes and near the surface. The second highlights the presence of sinkholes in cross section relative to an area without sinkholes (Figure 8b). In Figure 8a and 8b, the horizontal scale shows the location of the measurements on the surface and along the cross sections, and the vertical scale shows the different depths of the reflectance measurements. The reflectance strengths are represented by color-plate cuts, with positive amplitudes in black and negative amplitudes in blue tones. A cross section taken in April 2012 at the same location in "Ein Gedi South" (Figure 8c) was compared to the October 2011 analyses, to monitor the development of sinkholes in the area. In the western part, a new sinkhole can be seen right at the beginning of the section, and the development of this existing sinkhole at depth was observed.
It should be noted that the temporal changes in moisture content are found in limited locations within the plot. These changes, which are limited in scope rather than covering the complete area, are associated with the development of local subsurface sinkholes (and not to the possibility of reduced evaporation or increased moisture input, such as due to precipitation or groundwater table changes that are expected to occur throughout the area).
Spectral analysis of soil samples as a tool for mapping and detecting sinkhole hazard
The spectral properties of the soil collected at the research sites enabled their classification into two geographical groups: northern site and southern site. This classification was in agreement with Yechieli et al. (2002), who stated that in the northern part of the Dead Sea, the salt layer is either limited in extent or non-existent, whereas it is abundant in the southern part. Based on our results and earlier studies, it can be assumed at this stage that spectroscopic and hyperspectral aerial surveys will contribute to the finalization of the maps of sinkhole evolution in time and space. Our analysis revealed that spectroscopy can replace laboratory soil and mineralogy analyses for the mapping and classification of soil in the Dead Sea region.
Explanation for changes in EC within plots
The different measured EC values divided the area into a western region with lower EC values and an eastern region with higher EC values. These differences might be explained by the structural diversity of the soil cross section. The western region is characterized by sandy soil (the density and strength of the sand layers is unknown) with high permeability to water. The eastern region is characterized by clayey soil with high water-adsorption capacity and low permeability. Structural diversity might also exist due to the presence of buried underground soils.
Explanation for the differences in subsurface reflectance values between "Ein Gedi South" and "Ein Gedi North" plots
Subsurface reflection data results using GPR showed spatial changes resulting from the expansion of a sinkhole, identified by the time interval between the radar measurements. For example, in the eastern part of the "Ein Gedi South" plot, FDEM measurements and radar tools indicated a general expansion of the sinkhole area, with a region of potential sinkhole development to the southwest.
Combining remote-sensing methods enabled locating existing subsurface sinkholes, mapping them, and identifying areas with potential for new sinkhole development. Combining the various features of the active and passive methods enabled efficient mapping and monitoring of sinkholes at different developmental stages. This is because sinkhole formation is influenced by environmental factors in the subsurface soil, as seen in the layer cross sections.
Soil samples were taken from various sites on the shore of the Dead Sea, mainly the Ein Gedi Hot Springs (“South” and “North”), and their composition and characteristics were determined. Laboratory and remote-sensing analyses carried out on samples taken from the areas in which changes were monitored enabled distinguishing features, especially at sites where the soil might be thin. Initial results showed indicators on the surface of areas in which sinkholes are developing. These indicators were characterized by spectral signatures found at 1450, 1950, 2200 and 2300 nm. These results provide a potential direction for future research. The active and passive remote-sensing methods used in this study enabled monitoring and localizing sinkholes temporally and spatially.
The results indicated periodically detectable changes and, combined with accumulated knowledge of existing sinkhole locations, should enable predicting new sinkhole formation. Designers and engineers might implement the combined passive and active remote-sensing methods used in this study to plan and build better infrastructures on the ground and in the subsurface.
The methods presented in this study should be further developed, in combination with other approaches, such as hyperspectral mapping with modern and advanced sensors, thermal mapping, testing groundwater recharge in sinkholes and its correlation with EC and reflectance values, and combining hydrological and meteorological information with rainfall–runoff relationships.
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Citation: Goldshleger N, Basson U, Azaria I, Fastig S (2018) Using Combined Close-Range Active and Passive- Remote Sensing Methods to Detect Sinkholes. J Remote Sensing & GIS 7: 222. Doi: 10.4172/2469-4134.1000222
Copyright: © 2018 Goldshleger N, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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At long last: Fruitadens!!
Just in time to make it into the heterodontosaur part of my talk this
Butler, R.J., P.M. Galton, L.B. Porro, L.M. Chiappe, D.M. Henderson, and
G.M. Erickson. 2009. Lower limits of ornithischian dinosaur body size
inferred from a new Upper Jurassic heterodontosaurid from North America.
Proceedings of the Royal Society B 10.1098/rspb.2009.1494
The extremes of dinosaur body size have long fascinated scientists. The
smallest (<1 m length) known dinosaurs are carnivorous saurischian
theropods, and similarly diminutive herbivorous or omnivorous ornithischians
(the other major group of dinosaurs) are unknown. We report a new
ornithischian dinosaur, Fruitadens haagarorum, from the Late Jurassic of
western North America that rivals the smallest theropods in size. The
largest specimens of Fruitadens represent young adults in their fifth year
of development and are estimated at just 65-75 cm in total body length and
0.5-0.75 kg body mass. They are thus the smallest known ornithischians.
Fruitadens is a late-surviving member of the basal dinosaur clade
Heterodontosauridae, and is the first member of this clade to be described
from North America. The craniodental anatomy and diminutive body size of
Fruitadens suggest that this taxon was an ecological generalist with an
omnivorous diet, thus providing new insights into morphological and
palaeoecological diversity within Dinosauria. Late-surviving (Late Jurassic
and Early Cretaceous) heterodontosaurids are smaller and less ecologically
specialized than Early (Late Triassic and Early Jurassic)
heterodontosaurids, and this ecological generalization may account in part
for the remarkable 100-million-year-long longevity of the clade.
These specimens were collected before the first and third authors were even
born: part of the LACMs digs at the Fruita from back in the 1970s. They've
been referred to in the literature as the "Fruita Echinodon" or "Morrison
Echinodon" in previous reports.
Additional commentary at:
Thomas R. Holtz, Jr.
Email: email@example.com Phone: 301-405-4084
Office: Centreville 1216
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
Faculty Director, Earth, Life & Time Program, College Park Scholars
Faculty Director, Science & Global Change Program, College Park Scholars
Mailing Address: Thomas R. Holtz, Jr.
Department of Geology
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College Park, MD 20742 USA | <urn:uuid:c86720b2-f67f-4fd2-bd15-d0a2a990bc69> | 2.6875 | 669 | Comment Section | Science & Tech. | 40.976719 | 95,507,915 |
Further documentation is available here. Three dimensional mathematical shapes are also area volume formulas pdf volumes.
Displacement of liquid can also be used to determine the volume of a gas. The combined volume of two substances is usually greater than the volume of one of the substances. In SI the units of volume and capacity are closely related: one litre is exactly 1 cubic decimetre, the capacity of a cube with a 10 cm side. The cone is a type of pyramidal shape.
The fundamental equation for pyramids, one-third times base times altitude, applies to cones as well. A manifold has a volume form if and only if it is orientable. An orientable manifold has infinitely many volume forms, since multiplying a volume form by a non-vanishing function yields another volume form. Integrating the volume form gives the volume of the manifold according to that form. | <urn:uuid:82af8ca5-ea0e-4a8f-be4d-a7db92234ff9> | 3.578125 | 179 | Documentation | Science & Tech. | 28.900838 | 95,507,917 |
Eastern white pine (Pinus strobus L.) was often associated with oaks (Quercus spp.) on upland sites in presettlement forests of the upper Great Lakes region, but widespread logging and subsequent fires in the late 1800s converted these upland sites to fire-tolerant oak forests. Although white pine regeneration is occurring in these second-growth oak forests, white pine regeneration patterns in oak forests of the Great Lakes region are not well documented. We examined white pine regeneration in the southern Great Lakes region in an oak stand within the Oak Openings region of northwestern Ohio, where white pine plantations established in the 1940s have served as seed sources for white pine invasion of surrounding oak-dominated forests. White pine regeneration was aggregated in high-density clumps' in the oak stand, with a mean white pine to white pine nearest-neighbor distance of 1.8 m. Eighty-one percent of invading white pine established during a 6-yr interval that corresponded with an extended period of below-average annual available water deficits (i.e., conditions were more moist than normal). No white pine recruitment has occurred in the oak stand in the last 15 yr since the 6-yr establishment interval, and we hypothesize that favorable white pine colonization sites in the oak stand were occupied during the initial invasion event. White pine regeneration in these oak forests may proceed in "leaps and bounds," with white pine expanding 100-300 m by clumped regeneration into new areas during unique regeneration events. White pine's present ability to reproduce successfully in northwestern Ohio appears related to reductions of historic fire frequencies.
Forest fires; Forests and forestry; Great Lakes Region (North America); Oak; Ohio; Plant diversity; Reforestation; White pine
Botany | Environmental Sciences | Forest Sciences | Plant Sciences
Abella, S. R.,
MacDonald, N. W.
Spatial and temporal patterns of eastern white pine regeneration in the northwestern Ohio oak stand.
The Michigan Botanist, 41 | <urn:uuid:a6fb481c-52b1-447f-861b-a0b620effcb1> | 3.234375 | 408 | Academic Writing | Science & Tech. | 30.876918 | 95,507,926 |
Climate and extrema of ocean waves in the East China Sea
Wave climate plays an important role in the air-sea interaction over marginal seas. Extreme wave height provides fundamental information for various ocean engineering practices, such as hazard mitigation, coastal structure design, and risk assessment. In this paper, we implement a third generation wave model and conduct a high-resolution wave hindcast over the East China Sea to reconstruct a 15-year wave field from 1988 to 2002 for derivation of monthly mean wave parameters and analysis of extreme wave conditions. The numerical results of the wave field are validated through comparison with satellite altimetry measurements, low-resolution reanalysis, and the ocean wave buoy record. The monthly averaged wave height and wave period show seasonal variation and refined spatial patterns of surface waves in the East China Sea. The climatological significant wave height and mean wave period decrease from the open ocean in the southeast toward the continental area in the northwest, with the pattern generally following the bathymetry. Extreme analysis on the significant wave height at the buoy station indicates the hindcast data underestimate the extreme values relative to the observations. The spatial pattern of extreme wave height shows single peak emerges at the southwest of Ryukyu Island although a wind forcing with multi-core structure at the extreme is applied.
KeywordsWave climate East China Sea Extreme value analysis WaveWatch-III
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The authors would like to thank the SOED HPCC for their computational support, and WAFO group for supplying the code (http://www.maths.lth.se/matstat/wafo/). The CCMP wind product was provided by Earth Science Enterprise (ESE) of National Aeronautics and Space Administration (NASA). TP satellite significant wave height was downloaded from Jet Propulsion Laboratory of NASA (https://www.jpl.nasa.gov/). Comments and suggestions provided by anonymous reviewers are greatly appreciated. This work was supported by the National Natural Science Foundation of China (Grant Nos. 41476021, 41576013 & 41321004), the National High Technology Research and Development Program of China (Grant No. 2013AA122803), and National Program on Global Change and Air-Sea Interaction (Grant No. GASI-IPOVAI-04).
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Nathalie Cabrol is a planetary scientist at NASA Ames and a senior research scientist at the SETI Institute. But just because her research focuses on the geology, ecology, and history of faraway planets doesn’t mean she stares through a telescope all day. On the contrary, Cabrol holds the world record for the highest elevation dive by a woman. And she got her record in the name of science! Cabrol climbs some of the world’s highest mountains and dives into their lakes to understand what life on other planets may have been like in the past before climate change eliminated their surface water. Cabrol sat down to chat with us about her legendary dive in the Andes and how we can learn about other planets by studying our own.
How can you study Mars from Earth?
My field is on Mars. So that makes it a big commute to get there. So I chose to go, not exactly halfway, but I climbed some way towards it.
If you want to go to Mars, you want to know what is the environment in the past and was it suitable for life? I have to go to Mars analog environments. The higher you go on earth, the thinner the atmosphere is, the more UV, and the temperature changes are the same as they are on Mars at the equator (even today). A volcanic environment is a good analog.
This is what drove me to climb the high volcanoes in the Andes. I was interested in the combination of extremes. I am a lake person. My husband and I have been promoting the idea that there were lakes on Mars. Nobody had thought about the fact that water could have pooled. Once the idea was OK in the community, we went to those very high volcanic lakes to try to understand what the environment would have been like.
What does it take to get to the bottom of the lake at the top of a mountain?
Not being afraid to put a foot in front of the other. For a long time you have to think only about that and not about the goal which is the summit. Those are very high climbs -- 20,000 foot high mountains. In the Andes climbing to 20,000 feet you have all the mountain gear on you, it’s cold, you have to get acclimatized, you go with your colleagues, and when you get there they have become your friends too.
The year where we did our diving expedition we carried 500 kilograms. That’s half a ton of equipment and we were traveling light. Believe me, we had the most competitive diving equipment possible. It was very light.
You must have been a very adept diver...
I am a freediver. Normally I would dive without any breathing apparatus. I don’t have any specific issues at all with altitudes, so I didn’t feel going to the Andes was more difficult then to freedive than at sea level. But you have to be more careful. You don’t want to surface with your lungs empty because you only have half of the atmosphere to breathe up there. I realized very quickly I would not be able to document that lake if I was freediving.
[When altitude diving] you don’t want to surface with your lungs empty because you only have half of the atmosphere to breathe up there.
Freediving sounds terrifying. And you’re just doing it for fun?!
I once did that with Scott Parazynski, he’s a shuttle astronaut. We did a freedive together and when we got to the surface, I said: “Scott, how would you rank this out of 10?” and he looked at me and he said: “20!” This is coming from a guy who has been flying six times on the shuttle!
So had you ever done a Scuba dive before your Andes trip?
What I did first to prepare for the expedition was I finally certified Scuba. I am fearless. But there is one thing up to that point that I couldn’t get over and that was a pressurized vessel. I had that irrational fear of pressurized vessels, and this explains why I didn’t certify before. There was really no reason. I’m not the type of person that’s afraid. I had the answer one day talking to my mom serendipitously. She said: “You want me to explain to you why you’re afraid?” She said when I was less than a year old I was playing in the kitchen and the pressure cooker blew up and the lid flew one inch above my head. It was traumatic. I have no recollection of it, but I kept the fear. I’d see a gas tank or anything under pressure and I would make detours.
From that point on I was able to rationalize my fear. Pressurized vessels are much better now and the chances that it’s going to happen again are really small.
So I took on scuba diving.
You must have had to train pretty intensively, then, since you didn’t have much experience with Scuba...
Diving at this elevation has all sorts of concerns. You don’t want to dive with conventional air, you can get a bubble of air in your system and you can die. At 20,000 feet when you’re isolated that’s a very bad idea.
So we started talking about diving at 20,000 feet. It was clear that if people weren’t using rebreathers and pure oxygen we were going to get the bends. A year before at dinner I had met Dominique Sumian -- the chief expedition leader for Jacques Cousteau. I actually learned to freedive in the south of France in places he knew. I contacted him at that point and he said "come to San Diego with your team and we’ll certify you with military rebreathers."
That was perfect. It is really like a light backpack, with a scrubber. The civilian version would have done the trick, but it is three times heavier than this one. Now that we were training and getting certified and AquaLung was generous enough to loan us this equipment for our expedition for free.
What, exactly, is a rebreather?
We used the standard diving gear that you would use in the ocean. But the tank is the heaviest. The regular Scuba is a tank that you put on your back, attached to your floatation jacket, and you also have the lead belt. The rebreather is a bag containing a C02 scrubber that cleans the air you’re breathing and recycles it. So you don’t have any bubbles coming out. It’s a small bag: one foot by one foot. You have this tiny, tiny tank of oxygen that you’re breathing from and everything goes in the front, you have nothing to carry on your back, which gives you more mobility and freedom of movement.
Because of the elevation we needed a lot more lead than you would with the wet suit. I had about 40 lbs of lead and I’m 126 pounds. You can imagine how uncomfortable I was on land.
Because of the elevation we also had a dry suit and we needed a lot more lead than you would with the wet suit. I had about 40 lbs of lead and I’m 126 pounds. You can imagine how uncomfortable I was on land.
So what was it like, once you finished your training, to finally get up to top of the mountain and dive?
Diving there was an incredible experience. I came from being a pure freediver in June 2006 and being at the summit in November and doing this dive, which is still the highest dive in the world. For a woman I have the record.
Climbing those mountains is dangerous but not technical. It’s dangerous because it’s on loose rocks, big boulders, and they’re unstable and the earthquake risk is worse there than here in California.
You have to be resilient and resistant. It takes time. We have a camp at midslope and then a summit camp on the outer site of the crater. The volcano is dormant but not not extinct.
Once we arrived we had two dives we needed to do. We were three divers and a dive master and medical support on the shore. The first day I was taking samples and the other two divers were doing photography and video. I feel so comfortable in the water -- I feel more comfortable inside then out. But before I entered the water that day I was nervous. You train for three months and I spent so much time in the swimming pool at the bottom, I said you better give me a phone line at the bottom of the pool. If you want to find me, you’ll find me there. We had rehearsed everything. We had devised an interesting way of diving there because when you have a rebreather you don’t have any bubbles so people at the surface don’t know where you’re. It’s not safe.
What we did was something that solved a number of issues. Each of the divers had a float on top him or her. A buoy. Inside was a net with a GPS unit whose clock was coregistered with the clock on the camera we were holding down below and the bathymetric map we had completed the day before. Whenever we collected a sample, only by looking at the time stamp on the photo we would know exactly its coordinates and its place on the map.
We had a line from the buoy that was attached to our lead belt and we were repelling up and down the line so people on the shore knew where we were at all times. We could ascend easily and also attach a lot of equipment on the line with carabiners. So it was a mixture of climbing and diving.
The second day we made a transact of the lake and sampled for microbiology, for soil, and water chemistry. That day I was holding the camera. I was able to sit back and relax.
What did it look like?
The lake was completely transparent. Arctic blue. I photographed the rays of the sun piercing the water one by one.
It was a little over 5 meters deep [Editor: 16 feet] -- that’s an upgraded swimming pool.
I was suspended there filming panoramas and I was able to think about where I was. “OK lady, you’re at the summit of a volcano which is not exactly extinct on a very high mountain in the water in a diving suit.” I thought, if that thing blows up I’ll be the first diver in orbit. I’ll still have my breathing tank and a decent suit so maybe I can just wait to be picked up like a hitchhiker.
You completely lose the notion of time. This sense of being weightless. Everything was light. The sun diffracting in the water. It was just amazing.
You completely lose the notion of time. This sense of being weightless; despite all the lead, I didn’t feel it too much. Everything was light. The sun diffracting in the water. It was just amazing. It was literally out of this world.
But not. We learned a lot about the potential for life on Mars and its resistance to a high UV environment. I also was able see how this lake was changing so fast year by year and then it hit me that if this lake was showing me what Mars would have been like millions of years ago, it was also pointing to what was happening here and now on earth. That’s when I decided to push my research in parallel between life on other planets and climate change on our planet.
Did you have any trouble surfacing in the low atmosphere?
The NASA review board was concerned that after breathing pure oxygen for a while we might pass out after removing our rebreather. We’d be breathing an atmosphere that has much less oxygen. So we transitioned to medical oxygen for a little while.
We used so much energy the second dive. Each of us sucked up two tanks. We were high on oxygen! We broke camp inside the crater, broke the summit camp, and ran down in two hours. This is what too much oxygen will do to you.
But we didn’t pass out. With so much oxygen in our system it was hard to go to sleep.
How long did you spend diving?
The first dive we stayed down 25 minutes and the second dive was closer to 40 minutes. At this altitude that’s not a short dive. The second dive I was very, very comfortable. But one of my companions started to get cold. If one diver is not 100% you all go up. I was still filming them going up and then I realized they were going up but I was comfortable. And then I said: “You better get the hell out of here!”
Why do you have to do such a short dive when you’re up that high?
The first thing is that the water is 4 degrees C, that’s 37 or 38 degrees fahrenheit. That’s really, really, really cold. We have good clothes and we can fight hypothermia, but the cold temperature is one of the main drivers. You don’t want to start to get cold, you want to get out before that, because by the time you’re cold it’s too late. It’s interesting because I was never cold in the lake. But a few years ago I was diving in another lake, much lower, around 10,000 ft. The water was 12 C or 13 C and I was freediving for 1.5 hours--that requires a lot more energy because you have to go up and down. After an hour and 31 minutes I started to feel a little cold in my hands. Two minutes later it started bother me a lot and a minute later I needed to find a quick exit. I went in three or four minutes from feeling fine to saying: “OMG where’s the nearest exit?” When you start getting cold it’s too late.
Second, you don’t want to be exhausted. A rebreather is an interesting exercise. It’s a different beast. The mouthpiece can be a little hot. But you don’t want to be exhausted when you come to the surface because you need to spend energy getting to shore in an atmosphere that has half the normal pressure. And you only have 48 percent of the oxygen. In the Andes, by the time I got to the surface my rebreather mouthpiece was so hot I got rid of it and then I started swimming. But that was a huge mistake. Sprinting at this elevation is not a good idea. By the time I got to shore I was so exhausted I couldn’t pull myself out. I was on the shore and they dragged me a few feet. I had 40lbs of weight around my waist and that didn’t help. You’re not in your natural environment. At 20,000 feet no human being can live. There is no adaptation to very high elevation. That’s what we start calling the death zone. There are a number of reasons why you have to be more careful.
Could we expect a similar experience from putting humans on Mars?
We wear suits and are breathing oxygen so we were separated from the outside environment. This is the analogy. We dealt with that mission like a flight mission. We had an experimental protocol and we trained for many months. You see the divemaster going through the checklist and then you hear “Go!” It’s the real deal. We were looking at each other in the water for the first five minutes. I never checked my equipment so often in my life. But something caught my eye and got my attention, something I took a sample of, I saw the goal of our mission right there and forgot everything about the cumbersome aspect of the mission. Everything was fluid. We had done it over and over again in the swimming pool.
In that respect that was exactly like what an astronaut would do before a mission.
So, you’ve done this amazing dive and learned a ton of things about Earth and how Mars used to look. Where do you go from here?
I want to do more. Climate change and global warming are creating lakes even higher. I’m trying to get back there.
In the meantime I have a number of projects. I have one in the central Andes at a lower elevation. This one is to test technology and systems for exploring the lakes of Titan for a future mission. We’re developing a robot and floating platform. The question is: how do we explore alien lakes and seas remotely? We have lots of experience with rovers, but no robots that go on the water.
We’re developing a robot and floating platform. The question is: how do we explore alien lakes and seas remotely?
This is a project that, at the same time, allows us to approach exploration strategies of alien lakes and seas for Titan. We perform it in places being affected by climate change, which allows us to bring data supporting the study of climate change on Earth, but by the same token gives us information about what could have happened on Mars 3.5 billion years ago in analog environments, when the climate changed on the red planet. That’s a threefold project.
This is where the experience of the lakes we visited before in the Andes allows us to see differences in the deglaciation phases (the loss of ice due to global warming). First, you increase the amount of melt -- lots of ice is melting. You have more discharge in runoff, you’re eroding a lot more material because you have more power and energy in the stream, thus you bring more sediment into the lakes. The second phase is you melt so much ice that glacial streams have less discharge. All the sediment that was brought in before starts to settle down at the bottom of the lake. It’s a complete ecological catastrophe for the species in the lake because the lake becomes more transparent. More UV penetrates and the species that are not protected against them disappear...
Later, when glacial melt input stops, if there is no spring or precipitation, then the lake starts to evaporate. The lakes we’re studying in the high Andes are very far along in this process.
But in the Santiago areas in the central Andes it’s starting to happen right now.
Meanwhile, we also learn about what could have happened on Mars in similar conditions in the past, when Mars still had glaciers. We want to learn all the reasons why this is happening and the signatures of turbidity and temperature changes. In terms of robotic missions, these two parameters are relevant to Titan, not because of deglaciation but just because this is what happens in lakes: temperature and transparency change.
When I keep dry we’re doing the same thing in the desert, but with a rover. This is an application to a possible future mission that will be searching for life on Mars. We’re trying to build the right tools to detect subsurface life.
I have to ask, why explore the Earth and not attempt to become an astronaut yourself?
The more we learn about Mars the more we see the similarities with Earth and the potential for life to have evolved and still be there.
I wanted to be an astronaut, definitely. It’s the space program that died on me not the other way around. At the same time, there is also a multistep vision. There is a point in time when you say: “OK, let’s go there.” We did that for the moon. The more we learn about Mars the more we see the similarities with Earth and the potential for life to have evolved and still be there. It is extremely important that we do a very thorough job at understanding whether life is there or not. It should be done without human interference. We’re a microbial factory. The day we put a human on Mars we will find life on Mars. We should make a concerted and thorough effort to address that question. And we haven’t started yet. We’ve only addressed the habitability aspect -- and we have proven without a shadow of a doubt that it was, and still could be, habitable for microbial life as we know it. That’s why putting a human there would be a problem at this stage. We still need to complete that step of at least trying to find life and we haven't. VIKING wasn’t a rationalized try. The results are still very ambiguous today. Curiosity is not looking for life, it’s looking for the presence of organics. It cannot, unless a rabbit is jumping in front of the camera, find life.
We still need to put that mission or those missions at the surface of Mars before we can send a human. When that time comes I’ll be too old to be an astronaut. And I am fine with it. Because I don’t mind being a stepping stone on that process. I try to understand how to help finding this evidence of microbial life on Mars. In that sense, I am helping make steps towards the human exploration of Mars. The sooner we find these little critters (or have made or peace with the fact they might not be there), the sooner we can send a human crew. And this prospect is exciting. Meanwhile, we are learning a lot about our own planet by going to impossible places that we wouldn’t go to if not to understand some other fancy planet in the solar system. This is SO worth it. This is such an incredible journey. I’ll be an astronaut in my next life.
Not all science is done in a lab by guys in white coats staring into microscopes. Lots of discoveries require brave men and women to put their boots on the ground and get down and dirty in dangerous environments. Every month we’ll profile one of these field scientists, tell you how they do their job, and explain the science behind what they do. If there’s a scientist or field of science you’re dying to hear more about shoot us an email or a tweet: erin at erinbiba dot com, @erinbiba | <urn:uuid:2c420bd6-0738-467c-a6bc-3852802c46a5> | 2.8125 | 4,675 | Audio Transcript | Science & Tech. | 69.013966 | 95,507,953 |
Authors: George Rajna
Dynamic programming is a technique that can yield relatively efficient solutions to computational problems in economics, genomic analysis, and other fields. But adapting it to computer chips with multiple "cores," or processing units, requires a level of programming expertise that few economists and biologists have. Researchers at Lancaster University's Data Science Institute have developed a software system that can for the first time rapidly self-assemble into the most efficient form without needing humans to tell it what to do. Physicists have shown that quantum effects have the potential to significantly improve a variety of interactive learning tasks in machine learning. A Chinese team of physicists have trained a quantum computer to recognise handwritten characters, the first demonstration of " quantum artificial intelligence ". Physicists have long claimed that quantum computers have the potential to dramatically outperform the most powerful conventional processors. The secret sauce at work here is the strange quantum phenomenon of superposition, where a quantum object can exist in two states at the same time. One of biology's biggest mysteries-how a sliced up flatworm can regenerate into new organisms-has been solved independently by a computer. The discovery marks the first time that a computer has come up with a new scientific theory without direct human help. A team of researchers working at the University of California (and one from Stony Brook University) has for the first time created a neural-network chip that was built using just memristors. In their paper published in the journal Nature, the team describes how they built their chip and what capabilities it has. A team of researchers used a promising new material to build more functional memristors, bringing us closer to brain-like computing. Both academic and industrial laboratories are working to develop computers that operate more like the human brain. Instead of operating like a conventional, digital system, these new devices could potentially function more like a network of neurons. Cambridge Quantum Computing Limited (CQCL) has built a new Fastest Operating System aimed at running the futuristic superfast quantum computers. IBM scientists today unveiled two critical advances towards the realization of a practical quantum computer. For the first time, they showed the ability to detect and measure both kinds of quantum errors simultaneously, as well as demonstrated a new, square quantum bit circuit design that is the only physical architecture that could successfully scale to larger dimensions. Physicists at the Universities of Bonn and Cambridge have succeeded in linking two completely different quantum systems to one another. In doing so, they have taken an important step forward on the way to a quantum computer. To accomplish their feat the researchers used a method that seems to function as well in the quantum world as it does for us people: teamwork. The results have now been published in the "Physical Review Letters". While physicists are continually looking for ways to unify the theory of relativity, which describes large-scale phenomena, with quantum theory, which describes small-scale phenomena, computer scientists are searching for technologies to build the quantum computer. The accelerating electrons explain not only the Maxwell Equations and the Special Relativity, but the Heisenberg Uncertainty Relation, the Wave-Particle Duality and the electron's spin also, building the Bridge between the Classical and Quantum Theories. The Planck Distribution Law of the electromagnetic oscillators explains the electron/proton mass rate and the Weak and Strong Interactions by the diffraction patterns. The Weak Interaction changes the diffraction patterns by moving the electric charge from one side to the other side of the diffraction pattern, which violates the CP and Time reversal symmetry. The diffraction patterns and the locality of the self-maintaining electromagnetic potential explains also the Quantum Entanglement, giving it as a natural part of the Relativistic Quantum Theory and making possible to build the Quantum Computer.
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ok, so let's get some numbers first:
Delta Trianguli A: Age 8.5 Ga, Mass 1.0 Sols, Luminosity 1.5 Sols, Radius 1.2 Sols (G0 V).
Delta Trianguli B: Age 8.5 Ga, Mass 0.8 Sols, Luminosity 0.34 Sols, Radius 0.76 Sols (K2 V). (these are from my own stellar evolution tables)
Orbital separation = 0.11 AU, eccentricity = 0.02. ( http://www.solstation.com/stars2/del-tri2.htm
). Star1 = 0.0489 AU from barycentre, Star2 = 0.061 AU from barycentre.
Let's say your planet orbits the binary barycentre at a distance of 1.1 AU. It'd orbit the barycentre with a period of 316.67 days.
Since the planet orbits the pair, you need to calculate the temperature when the stars are at 90° (quadrature) to the planet and when the stars are in a line with the planet.
Let's assume for simplicity's sake that the planet doesn't move (the stars will be orbiting each other much more quickly, once every 10 days).
The planet starts with the stars lined up with it, with the primary closer. The planet is 1.051 AU from the G0 V, and 1.16 AU from the K2 V (which is eclipsed by the G0 V anyway). So it's just getting energy from the G0V, so it's basically a straightforward calculation with the first equation (L = 1.5, D = 1.051) so its blackbody temperature is about 300 K.
Five days later, the stars are in a line again but are reversed - the companion is the closer star to the planet. So here we use the first equation again (L = 0.34, D = 1.0389) and find that the planet's blackbody temperature is about 209 K. That's a big drop, but keep in mind that these eclipses are very short (not entirely sure how to calculate it, but it wouldn't be long - maybe an hour or so?). But also this assumes that the second star completely eclipses the first one, which in this case doesn't actually happen (if you calculate the angular diameter of each star, at this point the more distant primary would be 0.56 degrees and the closer companion would be 0.39 degrees, so some of the primary's radiation is still getting through and the temperature would be higher).
Between those times is when you'd use the second Flux equation. At quadrature (where the stars are at 90° to the planet), both stars are 1.011 AU from the planet. So the Flux from the primary star is (278.66^4) * (L/D²) = 601072003 * (1.5/1.212390123) = 7436616222. For the companion star, the Flux = 6010720039 * (0.34/1.213734568) = 1683765848. Add those together and you get 9120382070. Now the combined blackbody temperature would be (9120382070 ^ 0.25 = ) about 309 K.
The full temperature graph would look something like this:
graph.PNG [ 5.97 KiB | Viewed 61 times ]
Does that make any more sense? You really need a spreadsheet to calculate all this as you need to know where the stars are in their orbits etc. Not sure I can get into too much detail on it as I'm pretty rusty on all this now.
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The Baltic Sea is home to some of the world’s largest dead zones, areas of oxygen-starved waters where most marine animals can’t survive. But while parts of this sea have long suffered from low oxygen levels, a new study by a team in Finland and Germany shows that oxygen loss in coastal areas over the past century is unprecedented in the last 1500 years. The research is published in the European Geosciences Union journal Biogeosciences.
According to the researchers, human-induced pollution, from fertilisers and sewage running off the countries surrounding the Baltic into the sea, is the main driver of recent oxygen loss in the region’s coastal waters. The spread of low-oxygen areas can have dire consequences for the environment and for local populations as it can reduce fish yields and even lead to massive mortality of marine animals.
“The Baltic was strongly impacted by human nutrient inputs in the 20th century and is still experiencing the legacy of those inputs today,” said Tom Jilbert, an assistant professor at the University of Helsinki, Finland, who took part in the research. But despite recent measures to reduce the release of polluting nutrients, the researchers write in the new study that they found “no evidence of recovery” from oxygen depletion in the Archipelago Sea, a coastal area between mainland Finland and Sweden that is part of the Baltic.
A reason, they say, may be climate change. Since warm waters are less effective at holding oxygen, “global warming is likely to exacerbate oxygen depletion,” said Sami Jokinen, a researcher at the University of Turku, Finland, and lead-author of the Biogeosciences study. Jilbert added: “Climate change was not the main cause of the current dead zone, but it is an important factor delaying the recovery.”
To find out what fueled oxygen loss in the past and what role climate played, the team drilled and studied a 4-metre-long sediment core from the seafloor in the Archipelago Sea. This allowed them to see, for the first time, how oxygen levels changed in this area over the past 1500 years. This period includes the Medieval Climate Anomaly, a time of warmer climate but low nutrient pollution from 900 to around 1350, as well as modern times.
“The interesting finding from our study is that, in the coastal areas, oxygen loss in the modern period really stands out, due to the strong signal of recent human nutrient inputs,” said Jilbert. The team found that oxygen levels were also low during the warmer medieval period, but they write in their study that the present oxygen loss is “unprecedentedly severe,” showing how excess pollution and warmer temperatures can combine to make dead zones thrive.
The team also found that this recent oxygen loss started in the early 1900s, decades before it had been previously thought and prior to regular water-quality monitoring. “This is surprising because the 1950s is often regarded as the period of rising oxygen depletion in the Baltic Sea, which has been linked to the substantial increase in human-induced nutrient loading around that time,” said Jokinen. Landmass in the Baltic Sea area has been rising since the end of the Ice Age removed weighty ice sheets from the region, and this uplift makes some coastal areas more sensitive to oxygen loss. “On top of this, we found evidence of marked human-induced nutrient loading already at the turn of the 20th century, which likely stimulated oxygen depletion in coastal areas,” he continued.
This nutrient loading has long-term effects, making it hard to stop the ongoing spread of dead zones. Rivers in the inhabited coastlines of the Baltic carry nutrients into the sea, triggering algal blooms. As the algae die, they sink to the seafloor and are decomposed by bacteria, which use up oxygen in this process.
“If human nutrient inputs are reduced, this might be expected to reduce the blooms and shrink the dead zone,” explained Jilbert. But, in dead zones, the decaying algae release phosphorus more efficiently, which then flows back to surface waters where it leads to the growth of cyanobacteria (blue-green bacteria), which, in turn, capture nitrogen from the atmosphere. “As a result, the total amount of nutrients – phosphorus and nitrogen – in the water remains high even after human inputs have been reduced,” said Jilbert. “It is a self-sustaining vicious circle that can take decades to reverse,” adds Jokinen.
“Nowadays, and likely in the future, oxygen loss in the Archipelago Sea is sustained by the continued leakage of nutrients from the agricultural land, the release of phosphorus from the sediments to the water column due to low oxygen levels, and by the ongoing global warming,” said Jokinen. “Hopefully our study will contribute to the better recognition of climate change as a substantial driver of oxygen loss in the Baltic alongside human-induced nutrient loading. To achieve good ecological status in coastal areas under the projected global warming, the required reduction in nutrient input might be higher than previously thought,” Jokinen said.
“The good news is that many countries in the Baltic catchment have taken significant steps towards nutrient loading reductions,” said Jilbert. “In some coastal regions we are already seeing improvements. Better understanding of the balance between nutrient inputs and climate change will therefore help to guide management of the Baltic in the future.”
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Practical Issues, Marginals, Error Checks, and Error Correction
The usefulness of a new scientific technique is determined by the details of its implementation. Many clever techniques that are otherwise rigorous and sound fail to become useful workhorse laboratory techniques because of difficulties in experimental implementation, noise sensitivity, cumbersomeness, or other more fundamental limitations. Often these details go unreported (who wants to write a paper explaining how he failed to be able to do something?), resulting in a loss of valuable time and resources for research groups that attempt to use the technique. It’s therefore incumbent upon the developers of an experimental technique to determine whether practical limitations will render the technique less than ideal.
KeywordsPulse Spectrum Error Check Nyquist Rate High Point Density Spatial Chirp
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The incoming radiation at the upper level of a plant stand primarily depends on astronomic factors and large-scale meteorological processes, while the radiation characteristics of the ground surface determined by the reflection coefficient and relief of the surrounding ground can be considered to be of secondary importance. Therefore the incoming radiation is usually described by means of general actinoclimatological characteristics complemented with information on the surrounding ground.
KeywordsDiffuse Radiation Direct Solar Radiation Incoming Radiation Solar Elevation Atmospheric Transparency
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There are two laths in the garage opposite one another: one 2 meters long and the other 3 meters long. They fall against each other and lean against the opposite walls of the garage both laths and touch at a height of 70 cm above the garage floor. How wide is the garage?
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Determine the dimensions of cuboid a, b, c; if diagonal d=9 dm has angle with edge a α=55° and has angle with edge b β=58° | <urn:uuid:6bd04252-bc7c-4ee2-854b-a54b5d6ed198> | 2.953125 | 736 | Tutorial | Science & Tech. | 82.870542 | 95,508,012 |
|Scientific Name:||Vanvoorstia bennettiana (Harv.) Papenf.|
Claudea bennettiana Harvey, 1859
Sonderia bennettiana (Harvey) Müller ex J.Agardh, 1890
|Taxonomic Notes:||The genus Vanvoorstia contains three species. Vanvoorstia spectabilis and V. coccinea are common tropical (Indo-Pacific, including GBR) species, with the former also recorded from Lord Howe Island. While some confusion exists as to the exact differences between these two species (Price and Scott 1992), both are easily distinguished and considered very different from V. bennettiana, a very much smaller- and finer-meshed species in which the tetrasporangial stichidia are also easily defined.
There are now four species. Eric Coppejans (pers. comm.) indicates that there is a new species he described from East Africa which is probably Critically Endangered: Vanvoorstia incipiens De Clerck, Wynne & Coppejans (Phycologia 38 (1999): 394-400). This newly described species occurs massively in a single (rather small) bay along the east coast of Zanzibar, at about low tide level (large amounts drifting or entangled to other seaweeds in intertidal pools). Coppejans carried out over 200 collecting excursions along the Kenyan, Tanzanian (incl. Zanzibar) coast and NEVER found a single specimen anywhere else than the type locality, where we find it again year after year. It doesn't occur in the neighbouring bays, which look "identical" to this one! If that bay would be disturbed (harbour, oil pollution, etc.) the only known (type) locality would disappear and we would have a similar story there within the same genus!! Apparently some representatives do not succeed in colonizing larger areas!
|Red List Category & Criteria:||Extinct ver 3.1|
|Assessor(s):||Millar, A.J.K. (Royal Botanic Gardens Sydney, Australia)|
|Reviewer(s):||Paxton, J. (Australian Museum) & Coppejans, E. (University of Gent, Belgium)|
The red alga Vanvoorstia bennettiana has only ever been collected from two sites (in the world). The initial discovery, the type locality, was from the seabed at the eastern end of Spectacle Island in Parramatta River sometime between the 1st and the 16th May in 1855. This site is now operated by the Royal Australian Navy as an explosives storage (barge), administrative offices and a mooring site for destroyers and other large Naval vessels. The shoreline has been altered and strengthened and the seabed is regularly dredged to allow ample draught for large ships. This site was first surveyed by myself and colleague Mr Peter Richards in December 1988. Since then, seven dives during all seasons up until 23 April 2001, have been undertaken at that site. No specimens have been discovered, and the only alga found there was a species of the genus Sargassum, that appears to tolerate low light, high nutrient, regularly disturbed conditions.
The only other site known to have harbored this species was on the seabed between Point Piper and Shark Island in Port Jackson (Sydney Harbour). This was collected by Dr Ramsay of the Australian Museum in October 1886. This site was also surveyed by myself and colleague Mr Peter Richards firstly in December 1988 then numerous times (approx 10) since. The seabed in this area now has no solid rocky substrata to which any seaweed could attach, the sediment is approximately 1 m thick (a divers arm disappears to the shoulder) and is easily stirred up by divers and passing ferry traffic. The surrounding rocky foreshore of both Point Piper and Shark Island have only small amounts of the kelp Ecklonia radiata and the green alga Caulerpa filiformis growing on them. Both are known to tolerate heavily disturbed conditions. No specimens of Vanvoorstia bennettiana have been discovered.
Within Parramatta River and Port Jackson proper, I have logged some 50 dives from 12 different sites, all of which have reasonable coverage of a few marine algal species typical of the NSW coastline. Based on knowledge of two other species in the genus Vanvoorstia, in addition to known growth strategies and environmental preferences of other genera and species of the red algal family Delesseriaceae, to which Vanvoorstia bennettiana belongs, such areas should harbor this species. In 1913, the then Curator of Algae at the Royal Botanic Gardens Sydney, Arthur Lucas, published a paper in the Proceedings of the Linnaean Society of NSW in which he states "I have never obtained it [Vanvoorstia bennettiana] either cast up or by dredging." He was an active collector of algae along the NSW coast up until his death in 1936. The next Curator of Algae was Ms Valerie May who was also an active collector until her retirement in 1988, when I took over the position. She was also unable to rediscover this species.
Since 1980, I have logged in excess of 540 dives along the NSW coast as part of a state government research priority to document the entire marine algal flora of the coast. Our collections have come from Cape Howe in the very south of the state, to Cook Island on the Queensland/NSW border, with approximately 100 sites scattered in between. The red algal species Vanvoorstia bennettiana has not been discovered during any of these dives.
Several colleagues of mine from the universities of Southern Cross, New England, NSW, Sydney, and Wollongong, plus the Solitary Island Underwater Research Group (SURG), and the operators of every commercial dive shop I have worked through in NSW, have all been briefed on the identification of this and several other rare species of marine algae. None has reported a sighting during the 12 years I have been based at the Royal Botanic Gardens Sydney. The genus is known to have an isomorphic alternation of generations. This means that the haploid male and female macrophytic gametophytes are morphologically identical to the diploid macrophytic tetrasporophytes which they ultimately produce. There is no crustose or resting stage in the life cycle of the species, which may have allowed it to lie dormant for many years until environmental conditions were favourable. In short, both life stages are susceptible to the same environmental parameters.
The Extinct category is used 'when there is no reasonable doubt that the last individual has died.' With negative data there can always be some doubt. And new species continue to be found in Australian marine waters, even in Sydney Harbour (J.R. Paxton in litt.). The presence of 15 individuals in one collection indicates that the species was relatively common in at least one portion of Sydney Harbour at that time. Given the isomorphic alternation of generations, it seems most unlikely that the species would remain in existence and remain undetected for more than 100 years. Therefore as no specimens have been seen or collected in the intervening 116 years, despite numerous collections made by algologists in that period, the species can be considered truly Extinct.
|Range Description:||First collected/discovered (1855) by crude dredging as a single individual plant from the east end of Spectacle Island, in the Parramatta River, Port Jackson, Sydney Harbour, New South Wales, Australia. Second and last collection (1886) by dredging of approximately 15 individual plants from between Shark Island and Point Piper, Port Jackson, Sydney Harbour, New South Wales, Australia (8 kilometres east of Spectacle Island). Presently unknown.|
Regionally extinct:Australia (New South Wales)
|FAO Marine Fishing Areas:|
Pacific – southwest
|Range Map:||Click here to open the map viewer and explore range.|
|Habitat and Ecology:||Unknown at time of collection in 1855 and 1886. The two sites, and much of Sydney Harbour, presently has soft sediment seabed with scattered rocky reef and rocky intertidal shores. Scattered shells and solid waste products (cans, bottles etc.) also lie on the seabed.|
|Major Threat(s):||Sydney Harbour is in the middle of the city of Sydney, the largest metropolis in Australia with more than 4 million people. In the 200+ years since settlement, the harbour has been seriously degraded by the population explosion. Use of the harbour as recreational facility, port, source of food, and sewer has seriously impacted on the native flora and fauna. Even by 1880, the harbour was found to be overfished by a Royal Commission. The Major Threats that may have caused the extinction of this alga include large and small scale fisheries particularly trawling, infrastructure development including industry, human settlement, tourism/recreation, water transport [including dredging for ship passage], fisheries- related bycatch by netting, and water pollution from agriculture, domestic, commercial/ industrial, oil, sedimentation, and sewage. The water quality of the harbour has improved since the 1972 passage of the New South Wales Clean Waters Act and the more recent removal of sewage outfalls some kilometers offshore. More fish species have moved to the upper estuarine portions of the Parramatta River and whales have returned to the outer harbour. However, for sessile species of limited distribution like Bennetts seaweed, swimming out of the harbour was not an option and the damage was done, permanently. As we do not even know in which decade the extinction occurred, we will never know which of the major threats was causative; a combination of a number of those listed is likely. [Threats information provided by J.R. Paxton in litt.].|
|Conservation Actions:||Listed as a "Species Presumed Extinct" in section 4 of Schedule 4 of the Fisheries Management Act 1994, in the state of New South Wales, Australia. Listed as "Extinct" under the Environment Protection and Biodiversity Conservation Act 1999, by the Commonwealth of Australia.|
|Citation:||Millar, A.J.K. (Royal Botanic Gardens Sydney, Australia). 2003. Vanvoorstia bennettiana. The IUCN Red List of Threatened Species 2003: e.T43993A10838671.Downloaded on 22 July 2018.|
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Back in 2011, researcher Iain Kerr was having a frustrating day chasing sperm whales on the Gulf of Mexico. Kerr, CEO of the nonprofit Ocean Alliance, would wait to spot a whale surfacing. As soon as he did, he’d tell the crew to bring the research vessel to the mammal as quickly as possible so a researcher could shoot it with biopsy darts and extract a plug of skin and blubber to be analyzed. That day, the researchers found themselves rushing after surfacing sperm whales only to watch them dive before they could reach them — the whales can plunge as deep as 3,800 feet and stay below for more than 90 minutes. And this kept happening.
As Kerr sat in the bow of the boat and contemplated the day’s failure, a sudden cloud of whale blow — the spray exhaled by a whale — settled over him. And he had an unpleasant but scientifically fruitful realization. “It’s pretty fishy, pretty stinky stuff,” he says. Kerr knew the stink meant that biological material, not just water and air, was present. Which meant it might be worth sampling. But how could he get close enough to surfacing whales, and quickly enough, to catch the blow before they dove? Kerr, a drone aficionado, had an idea: why chase down a 4–6-mile-per-hour whale that can dive at any moment by using a boat that goes 8 miles an hour, when you could launch a drone that flies at 50 miles an hour?
Kerr began working with students at the Olin College of Engineering to design what they ended up calling the Parley SnotBot: a drone that could be launched from a research vessel, hover over a whale, and collect its blow. Although the technical term for the blow is “exhaled breath condensate,” Kerr calls the substance “snot” since it also includes the lubricants in a whale’s lungs and nasal tracts, along with other cells that get blown up and out. After trying to design their own drones and experimenting with the best ways to collect snot — including sponges, petri dishes hanging from poles and veil-like cloths — the team settled on a commercial drone mounted with petri dishes. (The drone was funded at first by a Kickstarter campaign and later in part by the nonprofit Parley for the Oceans.)
Since 2015, the Ocean Alliance has deployed SnotBot on seven expeditions. It’s collected over 500 samples of five species of whales in three areas — southern right whales off the coast of Patagonia; humpback whales and orcas off Alaska; blue whales in the Sea of Cortez in Mexico; and gray whales on the Pacific Ocean side of Baja California. On the expeditions, a researcher on the boat pilots the drone into the blow of a surfacing whale. While collecting snot, the drones also transmits photo and video of the whale back to scientists; when the whale dives, the pilot brings the drone home and the snot is harvested from its petri dishes. The team has also used drones to collect whale poop, drop underwater microphones, and fly over protected waters with a night-vision thermal camera to look for poachers.
The drone’s ability to take hi-res photos of the whale has been critically important and informative. A whale’s fluke, or its tail fin, is the species equivalent of human fingerprints — its particular color, scars and serration are unique to that animal. Previously, researchers took photos of whales’ flukes and then reviewed them one by one to match them to known subjects. But with this drone, that’s all changed. Special software designed by scientists at Intel harnesses artificial intelligence that instantly analyzes a fluke shape, compares it to images amassed from decades of whale research by the Alaska Whale Foundation and Happywhale, generates an ID, and brings up any existing data on the animal.
The software also gives an instant health check for the whale, even if its body is partially submerged. When it analyzes the photo, it’s able to estimate the mammal’s 2-D shape and provide a score known as Body Condition Index for researchers. This score can tell researchers on the spot if a whale is healthy or malnourished. Again, this immediacy is invaluable. “By arming researchers with this advanced ability to immediately understand and assess the state of things when they’re out in the field, they can take in the rest of the environment and put everything in context,” says Ted Willke, Intel’s senior engineer on the project. “Before, they’d have to go back to the lab and then realize after looking at photos that there was something else they should have been paying attention to.” He says the next step will be to train the software to recognize pregnant whales and juveniles and to identify where exactly on the whales they’re carrying fat, which will give researchers a greater understanding of how and when whales lose and gain blubber over the course of their feeding cycle.
Thanks to the drone, researchers can gather many more samples from whales — without disturbing them. University of Alaska–Fairbanks marine scientist Shannon Atkinson specializes in studying hormones in whales. She depends on getting snot and fecal samples to analyze. She echoes Kerr’s frustrations with traditional whale research: “You’re sitting around waiting for a whale to poop,” she laughs. “If they don’t have to go, you don’t get anything.” Before she had access to the drone, she collected about 110 blubber biopsies and 45 fecal samples in 10 years of expeditions. (Snot, even though it does contain hormones, was not collected before Kerr had his epiphany.) In a single 2017 expedition with the Parley SnotBot, Atkinson got 39 snot samples, and she’s collaborating with Ocean Alliance to analyze the hormones they contain. She won’t be retiring the pooper-scooper just yet; whale poop, rich in information about diet and nutrition, is useful in its own right. Another major advantage to the drone method is its noninvasive nature. Shooting biopsy darts at a whale usually causes it to dive down and hide — and, in some species, if one whale startles, that can scare the whole pod away, which means a researcher might get a sample from only one whale. So far, Kerr says there’s no evidence that the drone bothers the whales. “They’re quite used to having seagulls and birds flying around them,” he points out. And he believes the drone’s relatively high-frequency sounds don’t penetrate the water.
The hormones in whale snot will allow scientists to study whale pregnancies and stress levels. Atkinson’s lab has been able to isolate five different hormones from the blow: testosterone, progesterone, aldosterone, corticosterone and cortisol. Of special interest is progesterone, the hormone that allows mammals to maintain a pregnancy. Elevated amounts of it in blow indicate an expecting whale. (Fun fact: whales carry their young for 10 to 18 months before they give birth.) Atkinson hopes to track the reproductive rates of whale populations in order to monitor their overall health as a group. Examining levels of cortisol, a stress hormone, could show researchers how whales are reacting to, say, climate change or ocean noise.
What else can be found in whale blow? DNA! Scientists are using the genetic information to count individual whales and even trace matrilineal lines. Oregon State University conservation geneticist Scott Baker says that although the amount of DNA in blow is relatively low (compared to, say, blubber), its quality is high; along with water, whales exhale epithelial cells from their lungs. That’s good news for monitoring populations as they recover — or don’t — from their decimation due to commercial whaling in the 19th and 20th centuries, which Baker calls “one of the great challenges for whales and dolphins around the world.” Getting greater numbers of DNA samples means being able to get accurate counts of whales in different parts of the ocean.
This drone-enhanced view into the lives of whales gives us a window into how our oceans are doing. “We often think of whales as sentinels of the health of their ecosystem, because everything in that ecosystem is affecting them,” says Atkinson. Her lab is just beginning to analyze the drone-collected samples; she wants to study how pregnancy rates may have changed in humpback whales due to warming events in the Gulf of Alaska and how stress hormones may factor into that. Using the image-analyzing software to measure the “fatness” of a whale and then connecting that with stress levels and whether it’s pregnant or not, year after year, will give scientists a rich trove of data on individual whales. Look at those data points for entire populations of whales, and you can get an idea of what’s going on in the ecosystem on a larger scale. “That’s the kind of information we’re going to need, to understand the changes in the ocean over the next decade,” says Baker.
The drone has led to exciting moments for researchers. On a 2017 expedition in the Chatham Strait area of southeast Alaska, Willke was with the team on the boat as they listened to whale calls via underwater microphone. Suddenly, Alaska Whale Foundation marine biologist Fred Sharpe thought he heard a call that sounded familiar. Could it be Trumpeter, a whale he hadn’t encountered in 23 years? A drone snapped a photo of the whale from the air, and the software ran an analysis of the image against an old photo of Trumpeter: it was a 92 percent match. “It was astounding,” Willke says. Before the drone and AI technology, “there was no way they could have matched that animal.”
From the drone’s-eye view, says Kerr, “it’s a whole different world.” He explains, “I’ve got friends who are looking at my pictures saying, ‘I never knew they did that!’ and these people have been studying them for twenty years.” Scientists have gotten an up-close look at how humpback whales catch prey. Or, in a sweeter example, the Parley SnotBot has captured a never-bef0re-documented shot of a mother humpback whale stroking its calf with its pectoral fin. This kind of intimate, up-close footage has the potential to break through the cloistered world of researchers and inspire more people to feel connected with whales. In an interview with Oceans Deeply, Kerr asks, “Is this changing the field of biology? No. But does it make it easier for us to empathize with this creature? I think it does.”
Thanks to the drone, marine research is being revolutionized — at a bargain price. In summer 2018, the team plans to be off the coast of Massachusetts studying humpback whales, and later this year, they plan to go to Gabon, West Africa, to assess whale populations in an area where shipping traffic is increasing. It would be difficult and extremely expensive to get a fully staffed research vessel (which costs tens of thousands of dollars a day) to these waters, says Kerr, but a drone costs a few thousand dollars, a price low enough that the team will be able to leave one behind for people in Gabon to use. “Oceanography has, on many levels, been a prerogative of the privileged,” says Kerr. Drones can change that, opening up marine research to citizen scientists and to countries that can’t afford traditional programs. He adds, “I think we’re democratizing science with these drones.” | <urn:uuid:7d338eee-1320-477c-a3e7-243f2229a069> | 3.40625 | 2,493 | Truncated | Science & Tech. | 49.258961 | 95,508,017 |
A giant black hole ripped apart a nearby star and then continued to feed off its remains for close to a decade, according to research led by the University of New Hampshire. This black hole meal is more than 10 times longer than any other previous episode of a star's death.
"We have witnessed a star's spectacular and prolonged demise," said Dacheng Lin, a research scientist at UNH's Space Science Center and the study's lead author. "Dozens of these so-called tidal disruption events have been detected since the 1990s, but none that remained bright for nearly as long as this one."
Artist illustration depicting the record breaking "tidal disruption event" (TDE). The red shows hotter material that falls toward the black hole and generates a distinct X-ray flare. The blue shows a wind blowing from the infalling material.
Credit: CXC/M. Weiss; X-ray: NASA/CXC/UNH/D. Lin et al, Optical: CFHT
Using data from a trio of orbiting X-ray telescopes, NASA's Chandra X-ray Observatory and Swift Satellite as well as ESA's XMM-Newton, researchers found evidence of a massive "tidal disruption event" (TDE). Tidal forces, due to the intense gravity from the black hole, can destroy an object - such as a star - that wanders too close. During a TDE, some of the stellar debris is flung outward at high speeds, while the rest falls toward the black hole. As it travels inward, and is ingested by the black hole, the material heats up to millions of degrees and generates a distinct X-ray flare.
These multiwavelength flares, which can be viewed by the satellites, help to study otherwise dormant massive back holes. Previous flares were short-lived, typically becoming very faint in a year, but this super-long X-ray flare has been persistently bright for close to a decade. The extraordinary long bright phase of this TDE means that either this was the most massive star ever to be torn apart during one of these events, or the first where a smaller star was completely torn apart.
The X-ray source containing this force-fed black hole, known by its abbreviated name of XJ1500+0154, is located in a small galaxy about 1.8 billion light years from Earth.
The X-ray data also indicates that radiation from material surrounding this black hole has consistently surpassed the so-called Eddington limit, defined by a balance between the outward pressure of radiation from the hot gas and the inward pull of the gravity of the black hole.
The conclusion that supermassive black holes can grow, from TDEs and perhaps other means, at rates above those corresponding to the Eddington limit has important implications. Such rapid growth may help explain how supermassive black holes were able to reach masses about a billion times higher than the sun when the universe was only about a billion years old.
Based on the modeling by the researchers the black hole's feeding supply should be significantly reduced in the next decade and begin to fade in the next several years.
A paper describing these results appears in the February 6 issue of the journal Nature Astronomy which can be viewed here: http://www.
Lin received support for this work from NASA (Chandra Award Number GO5-16087X). The Chandra X-ray Observatory is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA.
The University of New Hampshire is a flagship research university that inspires innovation and transforms lives in our state, nation and world. More than 16,000 students from all 50 states and 71 countries engage with an award-winning faculty in top ranked programs in business, engineering, law, liberal arts and the sciences across more than 200 programs of study. UNH's research portfolio includes partnerships with NASA, NOAA, NSF and NIH, receiving more than $100 million in competitive external funding every year to further explore and define the frontiers of land, sea and space.
Robbin Ray | EurekAlert!
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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More Accurate Model of Climate Change’s Effect on Soil
News Aug 02, 2013
They found that soil outcomes based on their microbial model were more reliable than those forecast by traditional models. Study results appear online in Nature Climate Change.
While standard models project modest carbon losses with global warming, the microbial models generate two novel scenarios: One is that soil around the world will accumulate carbon if microbial growth declines with higher temperatures. The second assumes that microbial growth increases with global warming, resulting in large soil carbon losses, meaning much more carbon will be released into the atmosphere.
"The microbial soil model is extremely important to understanding the balance of carbon in the soil versus the atmosphere and how carbon mass in soil is affected by these bacteria and fungi," said the study's senior author, Steven Allison, an associate professor of ecology & evolutionary biology and Earth system science at UC Irvine. "Our hope is that this new soil model will be applied to the global Earth system models to better predict overall climate change."
The researchers also discovered that in cases of increased carbon input to soil (such as carbon dioxide or nutrient fertilization), microbes actually released the added carbon to the atmosphere, while traditional models indicate storage of the additional carbon. This, they said, is further evidence that the Earth system models should incorporate microbial impact on soil to more accurately project climate change ramifications.
"In our microbial model, we directly simulate how the activity of organisms like bacteria and fungi control the storage and losses of soil carbon," said Will Wieder, a postdoctoral scientist with the National Center for Atmospheric Research in Boulder, Colo. "Now that we can more accurately measure what happens to soil as temperatures increase, we hope to study the potential effects of soil carbon fluctuations within a changing environment."
Evolution Does Repeat Itself After AllNews
A team of University of Konstanz biologists led by Professor Axel Meyer shows that evolutionary outcomes can be predicted: In a new publication in the journal “Evolution Letters”, they are able to identify some of the factors that contribute to recurrent patterns of diversity and similarity in cichlids. | <urn:uuid:36056945-de1c-4b9b-a42c-f788061832d0> | 3.609375 | 428 | News Article | Science & Tech. | 9.500331 | 95,508,040 |
In the study of ecology, fisheries are considered as geographic areas where fish are harvested or raised for human consumption. The world’s fisheries are priceless natural resources which need to be managed properly to prevent fish populations from collapsing. Thus, when studying fisheries, researchers examine the health of fish communities and fish biodiversity.
Fisheries need to be managed for multiple reasons. For one, fish are not only an important economic resource, but are also valuable environmental indicators. For instance, fish can provide early signals of aquatic ecosystem decline or degradation. If the health of an aquatic community is in decline, fish populations and the quality of fish available will drop in accordance.
As mentioned, fisheries are a critical economic resource. However, the problems of over-fishing and exploitation are major issues. Over the past 50 years, since about the 1960s, 90% of global fish stocks have been overexploited1. The economic benefits of fisheries will become a relic of the past if these fish populations are continually harvested and not recovered.
Furthermore, overexploitation also disturbs the dynamics of fish populations. Different species of fish have different patterns for mating, they are a part of different food chains and so on. For example, red king crabs, which are found in the Bering Sea, have a mating pattern in which the males hold onto the females for ten days until all of the eggs are fertilized. Furthermore, females prefer to mate with large males, which have become scarce due to overfishing since the preferred crab to harvest is a large male. Unfortunately, overexploitation has resulted in a population which is in decline.
Fisheries are a complex issue. In order to properly manage fisheries it will require more than just government action, but the cooperation of all citizens. Thus, understanding fisheries and the critical role they play is imperative to learning how to better protect the world’s natural fish communities.
1. Frank, K.T., Petrie, B., Fisher, J.A.D., and Leggett, W.C. (2011). Transient dynamics of an altered large marine ecosystem. Nature, 477: 86-89.
Image Credit: BBC. (2012). How the world's oceans could be running out of fish. Retrieved from http://www.bbc.com/future/story/20120920-are-we-running-out-of-fish© BrainMass Inc. brainmass.com July 16, 2018, 10:15 pm ad1c9bdddf | <urn:uuid:cc1b7d2b-abc7-4bad-ad9f-7d8731aaaf4d> | 3.921875 | 521 | Knowledge Article | Science & Tech. | 46.611783 | 95,508,050 |
As described by the Kerr solution of Einstein's gravitational field equations, its spacetime geometry is completely characterized by only two numbers — mass and spin — and is sometimes described by the aphorism "black holes have no hair.''
A particle orbiting a rotating black hole always conserves its energy and angular momentum, but otherwise traces a complicated twisting rosette pattern with no discernible regularity.But in 1968, theoretical physicist and cosmologist Brandon Carter showed that the particle's wild gyrations nevertheless hold another variable fixed, which was named the "Carter constant.'' The true meaning of Carter's constant still remains somewhat mysterious 40 years after its discovery.
What's more, the deviation of the field's shape from being spherical is determined by a set of equations that are identical to those for Kerr black holes.
In his article "Carter-like Constants of the Motion in Newtonian Gravity and Electrodynamics" in the Feb. 12 issue of Physical Review Letters, Will points out that one Newtonian system that exhibits this property is surprisingly simple: two equal point masses at rest separated by a fixed distance.
"I was completely stunned when I saw that the Newtonian condition for a Carter constant was identical to the condition imposed by the black hole no-hair theorems," said Will. "Do I know why this happens? So far, not a clue.
"But what I really hope is that insights gained about this strange constant in the simpler Newtonian context will teach us something about how small black holes orbit around rotating massive black holes in general relativity, where the relativistic Carter constant plays a key role."
This will have implications for gravitational-wave astronomy, he says, because the signal from such events may be detectable by the advanced LIGO-VIRGO-GEO network of ground-based laser interferometric detectors or by the proposed space-based LISA (Laser Interferometer Space Antenna).
Will, who is also a visiting associate at the Institute of Astrophysics in Paris, is a theoretical physicist whose research interests encompass the observational and astrophysical implications of Einstein's general theory of relativity, including gravitational radiation, black holes, cosmology, the physics of curved spacetime and the interpretation of experimental tests of general relativity.
Will's "Was Einstein Right?" (1986) won the American Institute of Physics Science Writing Award. His "Theory and Experiment in Gravitational Physics" (1981) is considered the bible of the field.
His research was supported in part by the National Science Foundation, the National Aeronautics and Space Administration and the Centre National de la Recherche Scientifique, Programme Internationale de la Cooperation Scientifique.
Sue McGinn | EurekAlert!
Further reports about: > Energy > Gravitation > LIGO-VIRGO-GEO > Laser Interferometer Space Antenna > Physic > Science TV > Space > angular momentum > baldness of rotating black holes > black hole > black holes > gravitational field > ground-based laser interferometric detectors > rotating black hole > twisting rosette pattern
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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An ice cave is any type of natural cave (most commonly lava tubes or limestone caves) that contains significant amounts of perennial (year-round) ice. At least a portion of the cave must have a temperature below 0 °C (32 °F) all year round, and water must have traveled into the cave’s cold zone.
This type of cave was first formally described by Englishman Edwin Swift Balch in 1900 who suggested the French term "glacieres" should be used for them, even though the terminology of "ice caves" was then, as now, commonly used to refer to caves simply containing year-round ice. Among speleologists "ice cave" is the proper English language term.
|This section does not cite any sources. (January 2016)|
Bedrock caves are thermally insulated from the surface, so commonly assume a near-constant temperature approximating the annual average temperature at the surface. In some cold environments, average surface (and thus cave) temperatures are below freezing, and with surface water available in summer, ice caves are possible. However, many ice caves exist in temperate climates, due to mechanisms that result in cave temperatures being colder than average surface temperatures where they formed.
Cold traps - Certain cave configurations allow seasonal convection to import cold air from the surface in winter, but not warm air in summer. A typical example is an underground chamber located below a single entrance. In winter, cold dense air settles into the cave, displacing any warmer air which rises and exits the cave. In summer, the cold cave air remains in place as the relatively warm surface air is lighter and cannot enter. The cave will only exchange air when the surface air is cooler than the cave air. Some cold traps may ensnare surface snow and shade it from the summer sun’s rays, which may further contribute to the colder cave temperature.
Permafrost - Even temperate environments can include pockets of bedrock that are below freezing year round, a condition called permafrost. For example, winter wind and an absence of snow cover may allow freezing deep enough to be protected from summer thaw, particularly in light-colored rock that does not readily absorb heat. Although the portion of a cave within this permafrost zone will be below freezing, permafrost generally does not allow water percolation, so ice formations are often limited to crystals from vapor, and deeper cave passages may be arid and completely ice-free. Ice caves in permafrost need not be cold-traps (although some are), provided they do not draught significantly in summer.
Evaporative cooling - In winter, dry surface air entering a moisture-saturated cave may have an additional cooling effect due to the latent heat of evaporation. This may create a zone within the cave that is cooler than the rest of the cave. Because many caves have seasonally-reversing draughts, the corresponding warming of the cave through condensation in summer may occur at a different location within the cave, but in any event a moisture-saturated cave environment is likely to experience much more evaporative cooling than condensative warming.
Types of ice
|This section does not cite any sources. (January 2016)|
Different freezing mechanisms result in visually and structurally distinct types of perennial cave ice.
Ponded water - Surface water that collects and ponds in a cave before freezing will form a clear ice mass, and can be tens of metres thick and of great age. Large ice masses are plastic and can slowly flow in response to gravity or pressure from further accumulations. Sculpting from air flow and sublimation may reveal ancient accumulation bands within the ice.
Accumulated snow - Compressed under the weight of ongoing accumulations, snow sliding or falling into a cave entrance may eventually form ice that is coarsely crystalline, akin to glacier ice. True underground glaciers are rare.
Needle ice - Infiltrating water that freezes within the bedrock can sometimes be forced into the cave passage.
Intrusions - The weight of a surface glacier perched atop a cave entrance can force glacial ice a short distance into the cave. The only known examples of this phenomenon are the several 'ice plugs' at the back of Castleguard Cave in Alberta.
- Bandera Volcano Ice Cave (New Mexico, USA)
- Bixby State Preserve (Iowa, USA)
- Booming Ice Chasm (Alberta, Canada)
- Bortig Pit Cave (Apuseni Mountains, Romania)
- Canyon Creek Ice Cave (Alberta, Canada)
- Castleguard Cave (Alberta, Canada)
- Coudersport Ice Mine (Pennsylvania, USA)
- Decorah Ice Cave State Preserve (Iowa, USA)
- Demänovská Ice Cave (Slovakia)
- Dobšinská Ice Cave (Slovakia) UNESCO World Heritage site (2000)
- Eisriesenwelt (Werfen, Austria)
- Grotte Casteret (Aragon, Spanish Pyrenees)
- Ice Mountain (West Virginia, USA)
- Kungur Ice Cave (Perm Krai, Russia)
- Niter Ice Cave (Idaho, USA)
- Sam's Point Preserve (New York, USA)
- Scărișoara Cave (Romania)
- Shawangunk Ridge (New York, USA)
- Speilsalen (Norway) collapsed in 2007
- Víðgelmir (West Iceland)
- Macdonald, W.D. Mechanisms for Ice Development in Ice Caves of Western North America The Canadian Caver 25/1 and 25/2, 1993.
- Rachlewicz, G., Szczuciński, W. Seasonal, annual and decadal ice mass balance changes in Jaskinia Lodowa w Ciemniaku, the Tatra Mountains, Poland Theoretical and Applied Karstology, 17: 11-18, 2004. (documents ice mass loss in the Ciemniak Ice Cave, Poland).
- Balch, E.S. (1900). Glacieres or Freezing Caverns.
- Ford, Derek C.; Williams, P.W. (1989). Karst Geomorphology and Hydrology.
- "A Lexicon of Cave and Karst Terminology with Special Reference to Environmental Karst Hydrology" (PDF). Karst Waters Institute. 2002.
- Anonymous Eisriesenwelt: Scientific Background eisriesenwelt.at, undated, 7pp, retrieved January 2016.
- Barck, C. (December 1913). "Caves". Mazama. Portland, OR: Mazamas. 4 (2): 61–69. Retrieved February 20, 2016.
- Features of the Bandera Crater flow, Including Aa Lava & Ice CavesIce Cave at Bandera Volcano Virtual Field Trip to the basalts of the Zuni-Bandera Malpais, New Mexico Institute of Mining & Technology, 2000, retrieved 17 January 2016.
- Bortig Pit Cave – The Underground Ice World, Travel Guide Romania website, June 2014, retrieved 17 January 2016.
- Dobšinská Ice Cave Slovak Caves Administration, undated, retrieved 17 January 2016.
- Scarisoara Ice Cave – the biggest underground glacier in Romania, Travel Guide Romania website, December 24, 2014, retrieved 17 January 2016.
- The Virtual Cave: Ice Formations in Ice Caves goodearthgraphics.com
- Video of an ice cave in the Big Snowy Mountains of Montana YouTube video
- Rod Benson Big Ice Cave in the Pryor Mountains of Montana For Montana website, selfpublished, 2009, retrieved 17 January 2016.
- Eisriesenwelt Ice Cave photos Eisriesenwelt Austria, undated. retrieved 17 January 2016
- Kungur Ice Cave
- Durmitor Ice Cave
- Speleoglacio Ice Cave Research Group University of Milano, Italy[dead link]
- Marco Plebani GROTTE DI GHIACCIO Marco Plebani website, June 2009, 3pp (in Italian), retrieved 17 January 2016. | <urn:uuid:ea3b751e-a131-4fad-839b-eded1d817dfe> | 4.09375 | 1,716 | Knowledge Article | Science & Tech. | 32.712595 | 95,508,062 |
Typically, if you want to understand the foundation of something, building from the ground up sounds like a sensible approach. However, researchers in Dr. Ni’s group at Harvard have taken this idea a step further by building molecules one atom at a time. The group’s goal is to better understand the minimal requirements and exact properties of chemical reactions. For comparison, while every chemistry class … Continue reading Building the Smallest Chemical Beaker
It is 2018, and we are well on our way towards curing cancer. Yet, as we look around, we find another nightmare haunting our society that is as formidable, if not more so, as it has been for centuries. That nightmare is opioid addiction. Overcoming opioid addiction is notoriously difficult, because of the excruciating symptoms associated with the withdrawal process, during which the only aid … Continue reading The FDA Approves the First Non-Opioid Drug to Ease Opioid Withdrawal Symptoms
Is this apple safe to eat? Did that course of antibiotics work? To answer these types of questions we often need to know how to find and count illness-causing bacteria. Several bacteria counting techniques already exist. However, these approaches are slow and sensitive to laboratory conditions. Sam Nugen and his team from Cornell University are streamlining this process using a type of virus called phages, … Continue reading Viruses to the Rescue: Can we use viruses to find bacteria in our environment?
What is the hardest thing you think scientists need to do in a lab? Organic chemistry may not be the first thing that comes to mind, but multi-step organic syntheses are easily ranked a top challenge, even among experienced chemists. Nevertheless, computer scientists surprised us again with artificial intelligence (AI) which, despite having less chemistry experience than the average high-schooler, could prescribe recipes with success. … Continue reading AI advises chemists on how to make complex molecules
These colorful fractions were obtained upon purifying a synthetic small-molecule through flash column chromatography. Though most of these were impurities (bright colors in organic chemistry is usually not a great sign), it served as a reminder to appreciate the beauty in the mundane and seemingly unimportant. Contributed by Carmen Sivakumaren, a graduate student in the Biological and Biomedical Sciences Program at Harvard Medical School. Continue reading Spectrum
One of our Instagram followers won a print of this beautiful image! Be sure to follow us on Instagram @SITN_Harvard for your chance to win some SciArt. This beautiful contribution from Don Pottle is best described by the legend himself: “A few years ago, I was asked by a maker of contact lenses to examine a few samples of used contact lenses. There was a suspicion of … Continue reading Crystaleyes
By Andrew Wong, a second year graduate student in the Applied Physics program at Harvard University. The increase in global energy demand and subsequent carbon dioxide emissions has driven advancements in renewable energy generation technologies such as wind turbines and solar cells. However, these technologies are inherently intermittent, and require robust energy storage devices. Inexpensive, large-scale energy storage systems such as aqueous … Continue reading The Light of Elendil in Shelob’s Lair | <urn:uuid:63dab163-e226-4b98-85ba-12f168378e4f> | 2.59375 | 656 | Content Listing | Science & Tech. | 27.761143 | 95,508,076 |
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A contact explosive is a chemical substance that explodes violently when it is exposed to a relatively small amount of energy (friction, pressure, sound, light). Though different substances have varying amounts of energy sensitivity, they are all much more sensitive relative to other explosives. Contact explosives are a part of a group of explosives called primary explosives which are also very sensitive to stimuli but not to the degree of contact explosives. The extreme sensitivity of contact explosives is due to either its composition, bonds, or structure.
These are some common contact explosives.
|Compound||Sensitivity||Sensitive to||Type of Explosion|
|Acetone peroxide||High||Heat, flame, shock, friction||Entropic|
|Chlorine azide||Extreme||Friction, shock, chemicals||Energy, entropic|
|Copper(II) azide||Extreme||Shock, static||Energy|
|Fulminates||Very High||Friction, static, heat, flame, shock||Energy|
|Lead(II) azide||Very High||Shock, static||Energy|
|Nitrogen triiodide||Extreme ||Shock, alpha radiation||Energy, entropic|
|Nitroglycerin||Very High||Shock, friction||Energy, entropic|
|Picric acid (dry)||High||Shock, friction||Energy|
|Tetrasulfur tetranitride||Moderate||Shock, friction||Energy, entropic|
|Flash powder||High||Static, flame, friction||Energy, light|
Reasons for instability
Presence of nitrogen
Explosives that are nitrogen-based are incredibly volatile due to the stability of nitrogen in its diatomic state, N2. Most organic explosives are explosive because they contain nitrogen. They are defined as nitro compounds.
Since nitrogen wants to escape the unstable bonds it has in a big compound so that it can form its highly stable N2 form, it makes the compound sensitive to exploding. The presence of nitrogen in these explosives also makes them much more powerful. The triple bond that holds N2 together has an incredible amount of bond energy that when it forms it releases the nitrogen gas at high energies over a short period of time thus creating a huge explosion.
Oxidizer and fuel
Some contact explosives contain an oxidizer and a fuel in their composition. Chemicals like gasoline, a fuel, burn instead of explode because they must come into contact with oxygen in the combustion reaction. However, if the compound already contains both the oxidant and fuel, it produces a much faster and violent reaction.
Bonds and structure
The structures and bonds that make up a contact explosive contribute to its instability. Covalent compounds that have a large unequal sharing of electrons have the capability to fall apart very easily and explosively. Nitrogen triiodide is a perfect example of this property. The three huge iodine atoms try to attach themselves to one small nitrogen ion, which means that the atoms are holding on to each other through a very weak bond. The weak bond between each atom is like a thread just waiting to break. Therefore, any small amount of applied energy cuts this thread and releases the iodine and nitrogen atoms to react with the fuel, allowing the reaction to occur quickly and release a large amount of energy.
The shape of the contact explosive molecule plays a role in its instability as well. Using nitrogen triiodide as an example again, its pyramidal shape forces the three iodine atoms to be incredibly close to each other. The shape further strains the already weak bonds that holds together this molecule.
|Compound||Reason for Instability|
|Acetone peroxide||Composition allows for initiation reaction|
|Fulminates||Instability of fulminate ion|
|Nitrogen triiodide||Instable intramolecular bonds|
|Nitroglycerin||Nitrogen, Oxidizer and fuel|
|Picric acid (dry)||Nitrogen|
|Tetrasulfur tetranitride||Nitrogen, Instable intramolecular bonds|
|Flash Powder||Oxidizer and metallic fuel|
|Silver nitride||Instable intramolecular bonds|
Contact explosives are used in a variety of fields.
Militaries use a variety of contact explosives in combat. Some can be manufactured into different types of bombs, tactical grenades, and even explosive bullets. Dry picric acid, which is more powerful than TNT, was used in blasting charges and artillery shells. A lot of contact explosives are used in detonators. For explosives that use secondary explosives, contact explosives are used in the detonators to set off an energy chain reaction that will eventually set off the secondary explosive.
Compounds like lead azide are used to manufacture bullets that explode into shrapnel on impact.
Flash powders are used in a variety of military and police tactical pyrotechnics. Stun grenades, flash bangs, and flares all use flash powder to create bright flashing lights and loud noise that disorients the enemy.
On the other hand, many of these cheap, volatile contact explosives are also used in improvised explosive devices (IEDs) created by terrorists and suicide bombers. For example, acetone peroxide passes through explosive detectors and is incredibly powerful, unstable, and deadly. Evidence for the instability of these IEDs lies in the multiple reports of premature or wrongful IED explosions. However, when these explosives are used correctly, they have devastating consequences. The July 7th 2005 London bombings, the 2015 Paris attacks, and the 2016 Brussels bombings all used explosives that contained acetone peroxide.
Angina pectoris, an unfortunate symptom of Ischaemic heart disease, is treated with nitroglycerin. Nitroglycerin is known as a vasodilator. Vasodilators work by relaxing the heart's blood vessels so the heart does not need to work as hard. Picric acid specifically has been used for burn treatment and as an Antiseptic.
The same flash powder used for military tactical pyrotechnics can also be used for several theatrical special effects. They are used to produce loud, bright flashes of light for effect. Though some flash powders are too volatile and dangerous to be safely used, there are milder compounds that are still incorporated into performances today.
Silver Fulminate is used to make noise-makers, small contact poppers, and several other novelty fireworks. It is most widely used in bang snaps. In these small explosives, a minuscule amount of silver fulminate is encased in gravel and cigarette paper. Even with this small amount of silver fulminate, it produces a loud, sharp bang.
- Frierson, W. Joe, J. Kronrad, and A. W. Browne. "Chlorine Azide, CIN3. I1." - Journal of the American Chemical Society (ACS Publications). N.p., n.d. Web. 23 Oct. 2016.
- TheRoyalInstitution. "Slow Motion Contact Explosive - Nitrogen Triiodide." YouTube. YouTube, 27 Aug. 2015. Web. 09 Oct. 2016.
- "Nitro Compound." Wikipedia. Wikimedia Foundation, n.d. Web. 23 Oct. 2016.
- Senese, Fred. "Why Is Nitroglycerin Explosive?" General Chemistry Online: FAQ: Redox Reactions:. N.p., n.d. Web. 09 Oct. 2016.
- Cops, By. "Flash Bang 101." PoliceOne. N.p., n.d. Web. 04 Nov. 2016.
- Mosher, Dave. "The Homemade Explosive Used in the Paris Attacks Is a Chemical Nightmare." Business Insider. Business Insider, Inc, 16 Nov. 2015. Web. 01 Nov. 2016.
- "Nitroglycerin Sublingual: MedlinePlus Drug Information." Nitroglycerin Sublingual: MedlinePlus Drug Information. N.p., n.d. Web. 01 Nov. 2016.
- "Picric Acid for Severe Burns." Welcome. N.p., n.d. Web. 01 Nov. 2016.
- Admin. "Bang-Snaps and Silver Fulminate." Bang-Snaps and Silver Fulminate. N.p., n.d. Web. 04 Nov. 2016. | <urn:uuid:2c237920-47c9-4be6-b4ec-0e5c2438b46f> | 3.71875 | 1,754 | Knowledge Article | Science & Tech. | 37.69956 | 95,508,087 |
About microscopic forms of life, including Bacteria, Archea, protozoans, algae and fungi. Topics relating to viruses, viroids and prions also belong here.
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I would say that they would be able to live long enough to continue eating something but it is the enzymes signaled by the nucleus that makes the ameoba able to do other things. For example the digestion uses different parts of the ameoba's body to process things. These rely on enzymes to function which come from the nucleus.
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far-out wrote:Any eukariotic cytoplasm cannot long exist without a nucleus.
Not true, sieve tube members work very well without a nucleus
Ribosomal subunits are made in the nucleus, but it is a mistake to say that the ribosoms themselves are made there, since you can only call it a ribosome when the subunits are united, and that only happens in the cytoplasm, when they meet mRNA
"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter
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Scientists have discovered the brightest quasar in the early universe, powered by the most massive black hole yet known at that time. The international team led by astronomers from Peking University in China and from the University of Arizona announce their findings in the scientific journal Nature on Feb. 26.
The discovery of this quasar, named SDSS J0100+2802, marks an important step in understanding how quasars, the most powerful objects in the universe, have evolved from the earliest epoch, only 900 million years after the Big Bang, which is thought to have happened 13.7 billion years ago. The quasar, with its central black hole mass of 12 billion solar masses and the luminosity of 420 trillion suns, is at a distance of 12.8 billion light-years from Earth.
The discovery of this ultraluminous quasar also presents a major puzzle to the theory of black hole growth at early universe, according to Xiaohui Fan, Regents' Professor of Astronomy at the UA's Steward Observatory, who co-authored the study.
"How can a quasar so luminous, and a black hole so massive, form so early in the history of the universe, at an era soon after the earliest stars and galaxies have just emerged?" Fan said. "And what is the relationship between this monster black hole and its surrounding environment, including its host galaxy?
"This ultraluminous quasar with its supermassive black hole provides a unique laboratory to the study of the mass assembly and galaxy formation around the most massive black holes in the early universe."
The quasar dates from a time close to the end of an important cosmic event that astronomers referred to as the "epoch of reionization": the cosmic dawn when light from the earliest generations of galaxies and quasars is thought to have ended the "cosmic dark ages" and transformed the universe into how we see it today.
Discovered in 1963, quasars are the most powerful objects beyond our Milky Way galaxy, beaming vast amounts of energy across space as the supermassive black hole in their center sucks in matter from its surroundings. Thanks to the new generation of digital sky surveys, astronomers have discovered more than 200,000 quasars, with ages ranging from 0.7 billion years after the Big Bang to today.
Shining with the equivalent of 420 trillion suns, the new quasar is seven times brighter than the most distant quasar known (which is 13 billion years away). It harbors a black hole with mass of 12 billion solar masses, proving it to be the most luminous quasar with the most massive black hole among all the known high redshift (very distant) quasars.
"By comparison, our own Milky Way galaxy has a black hole with a mass of only 4 million solar masses at its center; the black hole that powers this new quasar is 3,000 time heavier," Fan said.
Feige Wang, a doctoral student from Peking University who is supervised jointly by Fan and Xue-Bing Wu at Peking University, the study's lead author, initially spotted this quasar for further study.
"This quasar was first discovered by our 2.4-meter Lijiang Telescope in Yunnan, China, making it the only quasar ever discovered by a 2-meter telescope at such distance, and we're very proud of it," Wang said. "The ultraluminous nature of this quasar will allow us to make unprecedented measurements of the temperature, ionization state and metal content of the intergalactic medium at the epoch of reionization."
Following the initial discovery, two telescopes in southern Arizona did the heavy lifting in determining the distance and mass of the black hole: the 8.4-meter Large Binocular Telescope, or LBT, on Mount Graham and the 6.5-meter Multiple Mirror Telescope, or MMT, on Mount Hopkins. Additional observations with the 6.5-meter Magellan Telescope in Las Campanas Observatory, Chile, and the 8.2-meter Gemini North Telescope in Mauna Kea, Hawaii, confirmed the results.
"This quasar is very unique," said Xue-Bing Wu, a professor of the Department of Astronomy, School of Physics at Peking University and the associate director of the Kavli Institute of Astronomy and Astrophysics. "Just like the brightest lighthouse in the distant universe, its glowing light will help us to probe more about the early universe."
Wu leads a team that has developed a method to effectively select quasars in the distant universe based on optical and near-infrared photometric data, in particular using data from the Sloan Digital Sky Survey and NASA’s Wide-Field Infrared Explorer, or WISE, satellite.
"This is a great accomplishment for the LBT," said Fan, who chairs the LBT Scientific Advisory Committee and also discovered the previous record holders for the most massive black hole in the early universe, about a fourth of the size of the newly discovered object. "The especially sensitive optical and infrared spectrographs of the LBT provided the early assessment of both the distance of the quasars and the mass of the black hole at the quasar's center."
For Christian Veillet, director of the Large Binocular Telescope Observatory, or LBTO, this discovery demonstrates both the power of international collaborations and the benefit of using a variety of facilities spread throughout the world.
"This result is particularly gratifying for LBTO, which is well on its way to full nighttime operations," Veillet said. "While in this case the authors used two different instruments in series, one for visible light spectroscopy and one for near-infrared imaging, LBTO will soon offer a pair of instruments that can be used simultaneously, effectively doubling the number of observations possible in clear skies and ultimately creating even more exciting science."
To further unveil the nature of this remarkable quasar, and to shed light on the physical processes that led to the formation of the earliest supermassive black holes, the research team will carry out further investigations on this quasar with more international telescopes, including the Hubble Space Telescope and the Chandra X-ray Telescope.
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Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
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Academics in Japan claim to have developed a form of self-healing glass - a discovery they stumbled upon almost completely by accident.
Glass made from a low-weight polymer called 'polyether-thioureas' can be made like new by applying a modest amount of pressure, they claim. That's compared to traditional glass that needs to be melted down and re-pressed.
Professor Takuzo Aida, from the University of Tokyo, led the research, published in the journal Science. He claims that the glass could eventually be used on smartphone screens and similar devices.
Self-healing materials aren't new. In the past, scientists have come up with rubbers and plastics that can reverse damage. However, the researchers believe that glass is the first hard substance capable of self-healing. Experts always thought that it would be impossible for such substances to heal at room temperature.
"High mechanical robustness and healing ability tend to be mutually exclusive," the researchers wrote in their paper.
They said that "in most cases, heating to high temperatures, on the order of 120°C or more, to reorganise their cross-linked networks, is necessary for the fractured portions to repair".
The researchers said the glass is "highly robust mechanically yet can readily be repaired by compression at fractured surfaces".
Surprisingly, graduate student Yu Yanagisawa discovered made this discovery by accident. Instead of trying to make self-healing glass, he was exploring ways the material could be used as a glue.
Speaking to Japan's NHK, he said: "I hope the repairable glass becomes a new environment-friendly material that avoids the need to be thrown away if broken."
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This article is missing information about marine or non-terrestrial herbivory.(March 2015)
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthparts adapted to rasping or grinding. Horses and other herbivores have wide flat teeth that are adapted to grinding grass, tree bark, and other tough plant material.
A large percentage of herbivores have mutualistic gut flora that help them digest plant matter, which is more difficult to digest than animal prey. This flora is made up of cellulose-digesting protozoans or bacteria.
- 1 Etymology
- 2 Definition and related terms
- 3 Evolution of herbivory
- 4 Food chain
- 5 Feeding strategies
- 6 Attacks and counter-attacks
- 7 Impacts
- 8 See also
- 9 References
- 10 Further reading
- 11 External links
Herbivore is the anglicized form of a modern Latin coinage, herbivora, cited in Charles Lyell's 1830 Principles of Geology. Richard Owen employed the anglicized term in an 1854 work on fossil teeth and skeletons. Herbivora is derived from the Latin herba meaning a small plant or herb, and vora, from vorare, to eat or devour.
Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in general are known as primary consumers. Herbivory is usually limited to animals that eat plants. Fungi, bacteria and protists that feed on living plants are usually termed plant pathogens (plant diseases), while fungi and microbes that feed on dead plants are described as saprotrophs. Flowering plants that obtain nutrition from other living plants are usually termed parasitic plants. There is, however, no single exclusive and definitive ecological classification of consumption patterns; each textbook has its own variations on the theme.
Evolution of herbivory
Our understanding of herbivory in geological time comes from three sources: fossilized plants, which may preserve evidence of defence (such as spines), or herbivory-related damage; the observation of plant debris in fossilised animal faeces; and the construction of herbivore mouthparts.
Although herbivory was long thought to be a Mesozoic phenomenon, fossils have shown that within less than 20 million years after the first land plants evolved, plants were being consumed by arthropods. Insects fed on the spores of early Devonian plants, and the Rhynie chert also provides evidence that organisms fed on plants using a "pierce and suck" technique.
During the next 75 million years, plants evolved a range of more complex organs, such as roots and seeds. There is no evidence of any organism being fed upon until the middle-late Mississippian, . There was a gap of 50 to 100 million years between the time each organ evolved and the time organisms evolved to feed upon them; this may be due to the low levels of oxygen during this period, which may have suppressed evolution. Further than their arthropod status, the identity of these early herbivores is uncertain. Hole feeding and skeletonisation are recorded in the early Permian, with surface fluid feeding evolving by the end of that period.
Herbivory among four-limbed terrestrial vertebrates, the tetrapods developed in the Late Carboniferous (307 - 299 million years ago). Early tetrapods were large amphibious piscivores. While amphibians continued to feed on fish and insects, some reptiles began exploring two new food types, tetrapods (carnivory) and plants (herbivory). The entire dinosaur order ornithischia was composed with herbivores dinosaurs. Carnivory was a natural transition from insectivory for medium and large tetrapods, requiring minimal adaptation. In contrast, a complex set of adaptations was necessary for feeding on highly fibrous plant materials.
Arthropods evolved herbivory in four phases, changing their approach to it in response to changing plant communities.
Tetrapod herbivores made their first appearance in the fossil record of their jaws near the Permio-Carboniferous boundary, approximately 300 million years ago. The earliest evidence of their herbivory has been attributed to dental occlusion, the process in which teeth from the upper jaw come in contact with teeth in the lower jaw is present. The evolution of dental occlusion led to a drastic increase in plant food processing and provides evidence about feeding strategies based on tooth wear patterns. Examination of phylogenetic frameworks of tooth and jaw morphologes has revealed that dental occlusion developed independently in several lineages tetrapod herbivores. This suggests that evolution and spread occurred simultaneously within various lineages.
Herbivores form an important link in the food chain because they consume plants in order to digest the carbohydrates photosynthetically produced by a plant. Carnivores in turn consume herbivores for the same reason, while omnivores can obtain their nutrients from either plants or animals. Due to a herbivore's ability to survive solely on tough and fibrous plant matter, they are termed the primary consumers in the food cycle (chain). Herbivory, carnivory, and omnivory can be regarded as special cases of Consumer-Resource Systems.
This section is missing information about an authoritative definition, that does not exclude non-mammal fauna (as snails graze on algae, caterpillars graze on leaves etc) .(March 2015)
Two herbivore feeding strategies are grazing (e.g. cows) and browsing (e.g. moose). Although the exact definition of the feeding strategy may depend on the writer, most authors[who?] agree that to define a grazer at least 90% of the forage has to be grass, and for a browser at least 90% tree leaves and/or twigs. An intermediate feeding strategy is called "mixed-feeding". In their daily need to take up energy from forage, herbivores of different body mass may be selective in choosing their food. "Selective" means that herbivores may choose their forage source depending on, e.g., season or food availability, but also that they may choose high quality (and consequently highly nutritious) forage before lower quality. The latter especially is determined by the body mass of the herbivore, with small herbivores selecting for high quality forage, and with increasing body mass animals are less selective. Several theories attempt to explain and quantify the relationship between animals and their food, such as Kleiber's law, Holling's disk equation and the marginal value theorem (see below).
Kleiber's law describes the relationship between an animal's size and its feeding strategy, saying that larger animals need to eat less food per unit weight than smaller animals. Kleiber’s law states that the metabolic rate (q0) of an animal is the mass of the animal (M) raised to the 3/4 power: q0=M3/4 Therefore, the mass of the animal increases at a faster rate than the metabolic rate.
Herbivores employ numerous types of feeding strategies. Many herbivores do not fall into one specific feeding strategy, but employ several strategies and eat a variety of plant parts.
|Algivores||Algae||krill, crabs, sea snail, sea urchin, parrotfish, surgeonfish, flamingo|
|Mucivores||Plant fluids, i.e. sap||Aphids|
Optimal Foraging Theory is a model for predicting animal behavior while looking for food or other resource, such as shelter or water. This model assesses both individual movement, such as animal behavior while looking for food, and distribution within a habitat, such as dynamics at the population and community level. For example, the model would be used to look at the browsing behavior of a deer while looking for food, as well as that deer's specific location and movement within the forested habitat and its interaction with other deer while in that habitat.
This model has been criticized as circular and untestable. Critics have pointed out that its proponents use examples that fit the theory, but do not use the model when it does not fit the reality. Other critics point out that animals do not have the ability to assess and maximize their potential gains, therefore the optimal foraging theory is irrelevant and derived to explain trends that do not exist in nature.
Holling's disk equation models the efficiency at which predators consume prey. The model predicts that as the number of prey increases, the amount of time predators spend handling prey also increases and therefore the efficiency of the predator decreases.[page needed] In 1959, S. Holling proposed an equation to model the rate of return for an optimal diet: Rate (R ) = Energy gained in foraging (Ef)/(time searching (Ts) + time handling (Th))
Where s = cost of search per unit time f = rate of encounter with items, h = handling time, e = energy gained per encounter
In effect, this would indicate that a herbivore in a dense forest would spend more time handling (eating) the vegetation because there was so much vegetation around than a herbivore in a sparse forest, who could easily browse through the forest vegetation. According to the Holling's disk equation, a herbivore in the sparse forest would be more efficient at eating than the herbivore in the dense forest
The marginal value theorem describes the balance between eating all the food in a patch for immediate energy, or moving to a new patch and leaving the plants in the first patch to regenerate for future use. The theory predicts that absent complicating factors, an animal should leave a resource patch when the rate of payoff (amount of food) falls below the average rate of payoff for the entire area. According to this theory, locus should move to a new patch of food when the patch they are currently feeding on requires more energy to obtain food than an average patch. Within this theory, two subsequent parameters emerge, the Giving Up Density (GUD) and the Giving Up Time (GUT). The Giving Up Density (GUD) quantifies the amount of food that remains in a patch when a forager moves to a new patch. The Giving Up Time (GUT) is used when an animal continuously assesses the patch quality.
Attacks and counter-attacks
The myriad defenses displayed by plants means that their herbivores need a variety of skills to overcome these defenses and obtain food. These allow herbivores to increase their feeding and use of a host plant. Herbivores have three primary strategies for dealing with plant defenses: choice, herbivore modification, and plant modification.
Feeding choice involves which plants a herbivore chooses to consume. It has been suggested that many herbivores feed on a variety of plants to balance their nutrient uptake and to avoid consuming too much of any one type of defensive chemical. This involves a tradeoff however, between foraging on many plant species to avoid toxins or specializing on one type of plant that can be detoxified.
Herbivore modification is when various adaptations to body or digestive systems of the herbivore allow them to overcome plant defenses. This might include detoxifying secondary metabolites, sequestering toxins unaltered, or avoiding toxins, such as through the production of large amounts of saliva to reduce effectiveness of defenses. Herbivores may also utilize symbionts to evade plant defences. For example, some aphids use bacteria in their gut to provide essential amino acids lacking in their sap diet.
Plant modification occurs when herbivores manipulate their plant prey to increase feeding. For example, some caterpillars roll leaves to reduce the effectiveness of plant defenses activated by sunlight.
A plant defense is a trait that increases plant fitness when faced with herbivory. This is measured relative to another plant that lacks the defensive trait. Plant defenses increase survival and/or reproduction (fitness) of plants under pressure of predation from herbivores.
Defense can be divided into two main categories, tolerance and resistance. Tolerance is the ability of a plant to withstand damage without a reduction in fitness. This can occur by diverting herbivory to non-essential plant parts or by rapid regrowth and recovery from herbivory. Resistance refers to the ability of a plant to reduce the amount of damage it receives from a herbivore. This can occur via avoidance in space or time, physical defenses, or chemical defenses. Defenses can either be constitutive, always present in the plant, or induced, produced or translocated by the plant following damage or stress.
Physical, or mechanical, defenses are barriers or structures designed to deter herbivores or reduce intake rates, lowering overall herbivory. Thorns such as those found on roses or acacia trees are one example, as are the spines on a cactus. Smaller hairs known as trichomes may cover leaves or stems and are especially effective against invertebrate herbivores. In addition, some plants have waxes or resins that alter their texture, making them difficult to eat. Also the incorporation of silica into cell walls is analogous to that of the role of lignin in that it is a compression-resistant structural component of cell walls; so that plants with their cell walls impregnated with silica are thereby afforded a measure of protection against herbivory.
Chemical defenses are secondary metabolites produced by the plant that deter herbivory. There are a wide variety of these in nature and a single plant can have hundreds of different chemical defenses. Chemical defenses can be divided into two main groups, carbon-based defenses and nitrogen-based defenses.
- Carbon-based defenses include terpenes and phenolics. Terpenes are derived from 5-carbon isoprene units and comprise essential oils, carotenoids, resins, and latex. They can have a number of functions that disrupt herbivores such as inhibiting adenosine triphosphate (ATP) formation, molting hormones, or the nervous system. Phenolics combine an aromatic carbon ring with a hydroxyl group. There are a number of different phenolics such as lignins, which are found in cell walls and are very indigestible except for specialized microorganisms; tannins, which have a bitter taste and bind to proteins making them indigestible; and furanocumerins, which produce free radicals disrupting DNA, protein, and lipids, and can cause skin irritation.
- Nitrogen-based defenses are synthesized from amino acids and primarily come in the form of alkaloids and cyanogens. Alkaloids include commonly recognized substances such as caffeine, nicotine, and morphine. These compounds are often bitter and can inhibit DNA or RNA synthesis or block nervous system signal transmission. Cyanogens get their name from the cyanide stored within their tissues. This is released when the plant is damaged and inhibits cellular respiration and electron transport.
Plants have also changed features that enhance the probability of attracting natural enemies to herbivores. Some emit semiochemicals, odors that attract natural enemies, while others provide food and housing to maintain the natural enemies’ presence, e.g. ants that reduce herbivory. A given plant species often has many types of defensive mechanisms, mechanical or chemical, constitutive or induced, which allow it to escape from herbivores.
Herbivore–plant interactions per predator–prey theory
According to the theory of predator–prey interactions, the relationship between herbivores and plants is cyclic. When prey (plants) are numerous their predators (herbivores) increase in numbers, reducing the prey population, which in turn causes predator number to decline. The prey population eventually recovers, starting a new cycle. This suggests that the population of the herbivore fluctuates around the carrying capacity of the food source, in this case the plant.
Several factors play into these fluctuating populations and help stabilize predator–prey dynamics. For example, spatial heterogeneity is maintained, which means there will always be pockets of plants not found by herbivores. This stabilizing dynamic plays an especially important role for specialist herbivores that feed on one species of plant and prevents these specialists from wiping out their food source. Prey defenses also help stabilize predator–prey dynamics, and for more information on these relationships see the section on Plant Defenses. Eating a second prey type helps herbivores’ populations stabilize. Alternating between two or more plant types provides population stability for the herbivore, while the populations of the plants oscillate. This plays an important role for generalist herbivores that eat a variety of plants. Keystone herbivores keep vegetation populations in check and allow for a greater diversity of both herbivores and plants. When an invasive herbivore or plant enters the system, the balance is thrown off and the diversity can collapse to a monotaxon system.
The back and forth relationship of plant defense and herbivore offense can be seen as a sort of "adaptation dance" in which one partner makes a move and the other counters it. This reciprocal change drives coevolution between many plants and herbivores, resulting in what has been referred to as a "coevolutionary arms race". The escape and radiation mechanisms for coevolution, presents the idea that adaptations in herbivores and their host plants, has been the driving force behind speciation.
While much of the interaction of herbivory and plant defense is negative, with one individual reducing the fitness of the other, some is actually beneficial. This beneficial herbivory takes the form of mutualisms in which both partners benefit in some way from the interaction. Seed dispersal by herbivores and pollination are two forms of mutualistic herbivory in which the herbivore receives a food resource and the plant is aided in reproduction.
Herbivorous fish and marine animals are an indispensable part of the coral reef ecosystem. Since algae and seaweeds grow much faster than corals they can occupy spaces where corals could have settled. They can outgrow and thus outcompete corals on bare surfaces. In the absence of plant-eating fish, seaweeds deprive corals of sunlight. They can also physically damage corals with scrapes.
The impact of herbivory can be seen in areas ranging from economics to ecological, and both. For example, environmental degradation from white-tailed deer (Odocoileus virginianus) in the US alone has the potential to both change vegetative communities through over-browsing and cost forest restoration projects upwards of $750 million annually. Agricultural crop damage by the same species totals approximately $100 million every year. Insect crop damages also contribute largely to annual crop losses in the U.S. Herbivores affect economics through the revenue generated by hunting and ecotourism. For example, the hunting of herbivorous game species such as white-tailed deer, cottontail rabbits, antelope, and elk in the U.S. contributes greatly to the billion-dollar annually hunting industry. Ecotourism is a major source of revenue, particularly in Africa, where many large mammalian herbivores such as elephants, zebras, and giraffes help to bring in the equivalent of millions of US dollars to various nations annually.
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- Sagers, C.L. (1992). "Manipulation of host plant quality: herbivores keep leaves in the dark". Functional Ecology. 6 (6): 741–743. doi:10.2307/2389971.
- Milchunas, D.G.; Noy-Meir, I. (October 2002). "Grazing refuges, external avoidance of herbivory and plant diversity". Oikos. 99 (1): 113–130. doi:10.1034/j.1600-0706.2002.990112.x.
- Edwards, P.J.; Wratten, S.D. (March 1985). "Induced plant defences against insect grazing: fact or artefact?". Oikos. 44 (1): 70–74. doi:10.2307/3544045.
- Pillemer, E.A.; Tingey, W.M. (6 August 1976). "Hooked Trichomes: A Physical Plant Barrier to a Major Agricultural Pest". Science. 193 (4252): 482–484. Bibcode:1976Sci...193..482P. doi:10.1126/science.193.4252.482. PMID 17841820.
- PNAS Vol 91 Jan 1994 a Review by Emanuel Epstein
- Langenheim, J.H. (June 1994). "Higher plant terpenoids: a phytocentric overview of their ecological roles". Journal of Chemical Ecology. 20 (6): 1223–1280. doi:10.1007/BF02059809.
- Heil, M.; Koch, T.; Hilpert, A.; Fiala, B.; Boland, W.; Linsenmair, K. Eduard (30 January 2001). "Extrafloral nectar production of the ant-associated plant, Macaranga tanarius, is an induced, indirect, defensive response elicited by jasmonic acid". Proceedings of the National Academy of Sciences. 98 (3): 1083–1088. doi:10.1073/pnas.031563398. PMC . PMID 11158598.
- Gotelli, NJ. A Primer of Ecology. Sinauer Associates Inc., Mass. 1995
- Gotelli 1995
- Smith, RL and Smith, TM. Ecology and Field Biology: Sixth Edition.Benjamin Cummings, New York. 2001
- Smith and Smith, 2001
- Gotelli, 1995
- Mead, R.J.; Oliver, A.J.; King, D.R.; Hubach, P.H. (March 1985). "The Co-Evolutionary Role of Fluoroacetate in Plant–Animal Interactions in Australia". Oikos. 44 (1): 55–60. doi:10.2307/3544043.
- Ehrlich, P. R.; Raven, P. H. (December 1964). "Butterflies and plants: a study of coevolution". Evolution. 18 (4): 586–608. doi:10.2307/2406212.
- Thompson, J. 1999. What we know and do not know about coevolution: insect herbivores and plants as a test case. Pages 7–30 in H. Olff, V. K. Brown, R. H. Drent, and British Ecological Society Symposium 1997 (Corporate Author), editors. Herbivores: between plants and predators. Blackwell Science, London, UK.
- Herrera, C.M. (March 1985). "Determinants of Plant-Animal Coevolution: The Case of Mutualistic Dispersal of Seeds by Vertebrates". Oikos. 44 (1): 132–141. doi:10.2307/3544054.
- "Plant-eating fish, Information sheets for fishing communities No 29". SPC (www.spc.int) in collaboration with the LMMA Network (www.lmmanetwork.org). n.d.
- An Integrated Approach To Deer Damage Control Publication No. 809 West Virginia Division of Natural Resources Cooperative Extension Service, Wildlife Resources Section West Virginia University, Law Enforcement Section Center for Extension and Continuing Education, March 1999
- Bob Strauss, 2008, Herbivorous Dinosaurs, The New York Times
- Danell, K., R. Bergström, P. Duncan, J. Pastor (Editors)(2006) Large herbivore ecology, ecosystem dynamics and conservation Cambridge, UK : Cambridge University Press. 506 p. ISBN 0-521-83005-2
- Crawley, M. J. (1983) Herbivory : the dynamics of animal-plant interactions Oxford : Blackwell Scientific. 437 p. ISBN 0-632-00808-3
- Olff, H., V.K. Brown, R.H. Drent (editors) (1999) Herbivores : between plants and predators Oxford ; Malden, Ma. : Blackwell Science. 639 p. ISBN 0-632-05155-8
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- website of the herbivory lab at Cornell University | <urn:uuid:8aab1729-27bd-4cac-8804-cad68949dea0> | 3.84375 | 6,913 | Knowledge Article | Science & Tech. | 51.854266 | 95,508,121 |
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Found most commonly in these habitats: 4 times found in Rainforest, 2 times found in Riparian vegetation, 2 times found in Acacia woodland, 2 times found in Riparian/Eucalyptus edge, 1 times found in Mulga, 0 times found in savannah woodland, 2 times found in mulga woodland, 2 times found in Eucalypt, open woodland, 2 times found in Eucalyptus woodland, 1 times found in Heath on sand, ...
Found most commonly in these microhabitats: 3 times Stray ground foragers, 2 times Stray foragers, 2 times ground forager(s), 2 times Forgaing column on Euc., 1 times Strays on low vegetation, 1 times Stray foragers on veget., 0 times sandy loam, 1 times random foragers, 0 times Pyrethrum knockdown, 1 times on Euc. salmonophloia, 0 times On E.deglupta, ...
Collected most commonly using these methods: 2 times ex pitfall trap, 1 times Pitfalls, 1 times hand collected.
Elevations: collected from 5 - 1280 meters, 368 meters average
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What is a pseudo force? Explain with the help of an appropriate example.
Solve the following problem using the concept of pseudo force:
Two rectangular blocks are stacked one over the other on a table. The lower and upper blocks have masses of 25 kg and 5 kg respectively. The coefficient of kinetic friction between the lower block and table is 0.3 and that between the two blocks is 0.6. A pulling force is applied to the lower block by means of a mass less rope attached to it.
a) Draw the free body diagram of the lower block "as seen" from the frame of reference of the table (or ground).
b) Draw the free body diagram of the upper block "as seen" i) from the frame of reference of the table (or ground), ii) from the frame of reference of the lower block.
c) At what acceleration of the lower block does the upper block start slipping relative to the lower block?
d) How much pulling force must be applied to the lower block to give it the acceleration calculated at c) above?© BrainMass Inc. brainmass.com July 16, 2018, 12:59 am ad1c9bdddf
Force is defined as an effort in the form of a push or pull applied on a body in order to change its state of rest or of uniform motion in a straight line. However, in an accelerated frame of reference this definition of force tends to break down. For example, when a vehicle accelerates suddenly, a passenger sitting in the vehicle is thrown back with a force. Nobody has pulled or pushed the passenger. In other words, no external force as defined above has been applied on the passenger; what then throws her back? The phenomenon is on account of a property of matter known as "inertia". Due to inertia the passenger has a tendency to continue to ...
The concept of pseudo force has been explained in details. To illustrate the application of the concept, solution to a problem has been provided using the concept of pseudo force. | <urn:uuid:13f40b36-9b9a-464c-88eb-a9a0fd46d0ad> | 4.1875 | 415 | Tutorial | Science & Tech. | 63.931331 | 95,508,152 |
GSA Bulletin articles published online ahead of print on 30 April
In a new paper published online by GSA Bulletin on 30 April, researchers Mark Richards and colleagues address the "uncomfortably close" occurrence of the Chicxulub impact in the Yucatán and the most voluminous phase of the Deccan Traps flood basalt eruptions in India. Specifically, the researchers argue that the impact likely triggered most of the immense eruptions of lava in India -- that indeed, this was not a coincidence, but a cause-and-effect relationship.
This photo shows a spectacular sigmoidal jointing within a very thick lava flow from the Ambenali formation in the Western Ghats area of India. See related open-access article by M.A. Richards et al.
Credit: M.A. Richards and colleagues, and GSA Bulletin
Knowledge and study of the Deccan Traps eruptions have consistently cast a shadow of doubt on the theory that the Chicxulub impact was the sole cause of the end-Cretaceous mass extinction, most infamous for killing off Earth's dinosaurs. But Richards and colleagues write that historical evidence for the triggering of volcanoes by large earthquakes, coupled with a wide range of data, show that the massive outpouring of Deccan lavas are likely to have been triggered by the Chicxulub impact -- and thus following on as a secondary disaster.
"The chances of that occurring at random are minuscule," says Richards. "It's not a very credible coincidence."
Several of the authors visited India in April 2014 to obtain lava samples for dating, and noticed that there are pronounced weathering surfaces, or terraces, marking the onset of the huge Wai subgroup flows. This geological evidence likely indicates a period of quiescence in Deccan volcanism prior to the Chicxulub impact, which, says Richards, "gave this thing a shake," thus mobilizing a huge amount of magma over a short period of time.
Richards and colleagues write that while the Deccan eruptions probably spewed massive amounts of carbon dioxide and other noxious, climate-modifying gases into the atmosphere, "It's still unclear if this contributed to the demise of most of life on Earth at the end of the Age of Dinosaurs."
This article is open access online. Co-authors of the paper are Paul Renne, Michael Manga, Stephen Self, and Courtney Sprain, all from UC-Berkeley; Walter Alvarez, a UC-Berkeley professor emeritus and the co-originator of the dinosaur-killing asteroid theory; Leif Karlstrom of the University of Oregon; Jan Smit of Vrije Universeit in Amsterdam; Loÿc Vanderkluysen of Drexel University in Philadelphia; and Sally A. Gibson of the University of Cambridge, UK. Learn more about this team's research via the UC-Berkeley newsroom. http://newscenter.
Triggering of the largest Deccan eruptions by the Chicxulub impact
Mark A. Richards et al., University of California, Berkeley, California, USA. Published online ahead of print on 30 Apr. 2015; http://dx.
Other GSA BULLETIN articles (see below) cover such topics as
1. A discussion of the coincidence of the eruption of the Siberian Traps with the end-Permian mass extinction;
2. An open-access article exploring a "brand-new" technique to understand the geochemistry of the Monterey Formation; and
3. New data regarding the Paleozoic evolution of western Marie Byrd Land, Antarctica.
GSA BULLETIN articles published ahead of print are online at http://gsabulletin.
Please discuss articles of interest with the authors before publishing stories on their work, and please make reference to GSA Bulletin in your articles or blog posts. Contact Kea Giles for additional information or assistance. Non-media requests for articles may be directed to GSA Sales and Service, email@example.com.
Siberian Traps volcaniclastic rocks and the role of magma-water interactions
B.A. Black et al., University of California, Berkeley, California, USA. Published online ahead of print on 30 Apr. 2015; http://dx.
The eruption of the Siberian Traps coincided with the end-Permian mass extinction. This work sheds light on the origin of unusual fragmental rocks from the Siberian Traps, their significance for the extent of Siberian Traps explosive volcanism, and implications for the delivery of volcanic gases to the upper atmosphere.
Diagenesis of phosphatic hardgrounds in the Monterey Formation: A perspective from bulk and clumped isotope geochemistry
H.J. Bradbury et al., Imperial College London, London, UK. Published online ahead of print on 30 Apr. 2015; http://dx.
Phosphorus is an essential element of the biological cycle, and can form a significant mineral fraction in sediment. This paper shows for the first time the temperature at which phosphorus nodules recrystallized within sediments of the Monterey Formation, shedding light on the geochemical processes taking place in a world-class source rock, and opening up the application of a brand new technique to understand phosphorus-rich sediments deposited on continental margins around the world.
Paleozoic evolution of western Marie Byrd Land, Antarctica
C. Yakymchuk et al., Laboratory For Crustal Petrology, University of Maryland, College Park, Maryland, USA. Published online ahead of print on 30 Apr. 2015; http://dx.
Understanding of the geological history of West Antarctica has been hindered by difficult access and the near absence of outcrops in this vast ice-covered region. Chris Yakymchuk and colleagues report new geochemical data from rare sedimentary and igneous rocks that crop out above the West Antarctica Ice Sheet that provide new insights into the Paleozoic tectonic and geological evolution of this poorly understood part of Antarctica. Cambrian-Ordovician sedimentary rocks preserve a history of sedimentation from source rocks now exposed in the Transantarctic Mountains and from rocks that now lie beneath the East Antarctic Ice sheet. Igneous rocks record Paleozoic subduction-related magmatism that is different to broadly contemporaneous magmatism in New Zealand and Eastern Australia -- regions that were once contiguous with West Antarctica along the former active margin of East Gondwana in the Pangean supercontinent. This indicates that different tectonic modes operated simultaneously along an ancient active continental margin system.
Are aragonite stalagmites reliable paleoclimate proxies? Tests for oxygen isotope time series replication and equilibrium
M.S. Lachniet, University of Nevada, Las Vegas, Nevada, USA. Published online ahead of print on 30 Apr. 2015; http://dx.
Cave deposits have been increasingly used to study past climate variations and have contributed important breakthroughs for understanding of the controlling factors that govern Earth's climate system. Most cave deposits are composed of the mineral calcite, but recent work has used aragonite stalagmites. However, how well aragonite stalagmites record climate variation is not well known, thus limiting paleoclimatologists' confidence in their oxygen isotopic records. In this new paper, Matthew S. Lachniet shows that aragonite stalagmites in some cases are exceptionally robust climate records, but that in other cases their oxygen isotopic composition may not reflect equilibrium, and hence climate, variations. Replicated aragonite stalagmite records are required to have confidence in their use as paleoclimate proxies.
A cold supergene zinc deposit in Alaska: The Reef Ridge case
L. Santoro et al., Università degli Studi di Napoli Federico II, Napoli, Italy. Published online ahead of print on 30 Apr. 2015; http://dx.
The Reef Ridge deposit (Alaska) is a typical supergene "nonsulfide" zinc mineralization, where smithsonite is the predominant ore mineral. The carbon and oxygen isotope values of smithsonite vary, and the delta-13C values are similar to those of the host rock, which is the predominant carbon source. The oxygen isotope ratios are more depleted in 18O compared to supergene nonsulfides from other parts of the world, formed under warm-humid, temperate or semi-arid climates. These values indicate that the delta-18O composition of Reef Ridge smithsonite is related to very low formation temperatures (approx. 10 degrees C), and strong depletion in 18O of the precipitating waters. The Reef Ridge nonsulfides were formed during cold/humid weathering episodes (late Tertiary to Recent). The "traditional" interpretation on the genesis of Zn nonsulfide deposits in warm-humid, temperate or semi-arid conditions, writes author L. Santoro, should be questioned where other climate zones are indicated.
New insights into the emplacement mechanism of the Late Triassic granite plutons in the Qinling orogen: A structural study of the Mishuling pluton
W. Liang et al., State Key Laboratory of Continental Dynamics, Northwest University, Xi'an, China. Published online ahead of print on 30 Apr. 2015; http://dx.
From the abstract: Numerous geochronological and geochemical studies of the Late Triassic granite plutons in the Qinling orogen have been conducted over the past few decades. These studies have extensively discussed the genesis and correlations of granite plutons with the collisional processes between the North and South China blocks. However, several contradictory conclusions on the tectonic settings of these plutons (subduction, syn-collision, post-collision or intraplate) have been reached. Moreover, in all these studies, compressional or extensional structures have been always considered to control the magma emplacement, but no direct evidence has been presented so far. In order to clarify the emplacement mechanism of these Late Triassic plutons and avoid the ambiguities from pure geochemical studies, we conducted a multidisciplinary structural study on the Mishuling pluton in the West Qinling, one of the biggest Late Triassic plutons in the orogen.
Contact: Kea Giles
Kea Giles | EurekAlert!
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
Drones survey African wildlife
11.07.2018 | Schweizerischer Nationalfonds SNF
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
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Description: Objectives: differentiate between the good and bad ozone, locate the position in the atmosphere where the good and bad ozone reside, plot monthly ozone data and understand the ground level ozone effects on humans and plants..
Created by: Chris Sheehan Added: 2009-03-07
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The continued strength of this site depends on teacher contributions. Please help make this site stronger by submitting a file today. Submitting is easy, simply click here to get started. Thanks!
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Secure Real-Time Transport Protocol (SRTP) Library
The libSRTP library is an open source implementation of the Secure Real-time Transport Protocol (SRTP) originally authored by Cisco Systems, Inc. SRTP is a security profile for RTP that adds confidentiality, message authentication, and replay protection to that protocol. It is specified in RFC 3711. More information about the SRTP protocol itself can be found on the Secure RTP page.
Source Files (show merged sources derived from linked package)
|_link||0000000451451 Bytes||1413983642over 3 years ago| | <urn:uuid:7b6599a5-f57e-4c46-95c4-7d4110dd1b39> | 2.515625 | 125 | Documentation | Software Dev. | 34.448571 | 95,508,169 |
Experts from the Met Office, the University of Exeter and the Centre for Ecology & Hydrology, have found that projections of increasing ozone near the Earth’s surface could lead to significant reductions in regional plant production and crop yields. Surface ozone also damages plants, affecting their ability to soak up carbon dioxide from the atmosphere and accelerating global warming.
Near-surface ozone has doubled since 1850 due to chemical emissions from vehicles, industrial processes, and the burning of forests. Dr Stephen Sitch, a climate impacts scientist at the Met Office Hadley Centre and lead author of the article, said: “Climate models have largely ignored atmospheric chemistry but in this research we have identified a cause of potentially increased warming with elevated levels of surface ozone likely to suppress plant growth.”
Plants and soil are currently slowing–down global warming by storing about a quarter of human carbon dioxide emissions, but the new study suggests that this could be undermined by further increases in near-surface ozone. As a result more carbon dioxide would accumulate in the atmosphere and add to global warming. Co-author, Professor Peter Cox of the University of Exeter, explains: “We estimate that ozone effects on plants could double the importance of ozone increases in the lower atmosphere as a driver of climate change, so policies to limit increases in near-surface ozone must be seen as an even higher priority"
Sarah Hoyle | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
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Gravitational Force MCQs Quiz Worksheet PDF Download
Practice gravitational force MCQs, science test for online course learning and test prep. Forces quiz questions has multiple choice questions (MCQ), gravitational force test to learn.
Science practice test MCQ on gravitational force is influenced by object's with options weight, shape, size and color problem solving skills for competitive exam, viva prep, interview questions with answer key. Free science revision notes to learn gravitational force quiz with MCQs to find questions answers based online learning tests.
MCQs on Gravitational Force Quiz PDF Download
MCQ. Gravitational force is influenced by object's
MCQ. Weight is considered as
MCQ. Gravitational force is defined as the force of attraction between
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MCQ. If you leave a ball on slanting surface due to gravity it will move
- down the slope
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- gravitational force | <urn:uuid:40ee6f7d-def9-4308-9c60-2688d27abce0> | 3.578125 | 214 | Product Page | Science & Tech. | 44.970333 | 95,508,199 |
Mexican free-tailed bat
|Mexican free-tailed bat|
|Song of male, slowed eight times|
(I. Geoffroy, 1824)
|Range of the Mexican free-tailed bat|
The Mexican free-tailed bat or Brazilian free-tailed bat (Tadarida brasiliensis) is a medium-sized bat that is native to the Americas, regarded as one of the most abundant mammals in North America. Its proclivity towards roosting in huge numbers at relatively few locations makes it vulnerable to habitat destruction in spite of its abundance. The bat is considered a species of special concern in California as a result of declining populations. It has been claimed to have the fastest horizontal speed (as opposed to stoop diving speed) of any animal, reaching top ground speeds of over 160 km/h; its actual air speed has not been measured.
Molecular sequence data indicates T. brasiliensis's closest relatives are the sister species Sauromys petrophilus of South Africa and Tadarida aegyptiaca of Africa and south Asia. These three species form a clade believed to be about 6.5 million years old.
Mexican free-tailed bats are on average 9 cm (3.5 in) in length and weigh approximately 7–12 g (0.25–0.42 oz) with females tending to be slightly heavier than males by one or two grams for increased fat storage to use during gestation and nursing. Their tail is almost half their total length and stretches beyond the uropatagium, giving them the name "free-tailed" bats. Their ears are wide, rounded, and large compared to their head, nearly meeting at the front of the face but distinctly not joined at the midline and projecting anterodorsally from just before the muzzle to the back of the head. They use their large ears to help them find prey using echolocation. T. brasiliensis is distinguished among North American Tadarida bats in possessing deep wrinkles on the upper lip and in having a Z-shaped upper third molar which is used for grinding insects. These individuals possess canines which are larger in males than in females. The wings are elongated and narrow with pointed tips, making them well-equipped for quick, straight flight patterns. Their fur color ranges from dark brown to gray. The Mexican free-tailed bat's large feet have distinct long, white bristles. The dental formula of Tadarida brasiliensis is 18.104.22.168.
Range and ecology
The Mexican free-tailed bat ranges from the southern half of the continental United States through most of Mexico, and through most of Central America into South America. The range of the Mexican free-tailed bat in South America is less understood where it lives in the eastern Brazilian highlands and coast, the northeastern Andes and the coast of Peru and northern Chile. It is absent in much of the Amazon rainforest. The bat is also found in the Caribbean, and is native to all of the Greater Antilles and 11 of the Lesser Antilles. The largest known colony is found at Bracken Cave, north of San Antonio, Texas, with nearly 20 million bats; research indicates the bats from this colony congregate in huge numbers at altitudes between 180 and 1,000 m (590 and 3,280 ft), and even as high as 3,000 m (9,800 ft).
Mexican free-tailed bats roost primarily in caves. However, they will also roost in buildings of any type as long as they have access to openings and dark recesses in ceilings or walls. The bats can make roosting sites of buildings regardless of "age, height, architecture, construction materials, occupancy by humans and compass orientation". Caves, on the other hand, need to have enough wall and ceiling space to fit millions of bats. Before buildings, free-tailed bats in the southeastern United States probably roosted in the hollows of trees such as red mangrove, black mangrove, white mangrove and cypress. However, most bats in Florida seem to prefer buildings and other man-made structures over natural roosts. Caves in Florida tend to be occupied mostly by the southeastern myotis. Caves in Florida tend to have pools of water on the floor and the free-tailed bats do not need as much relative humidity as the southeastern myotis.
Mexican free-tailed bats in southeastern Nevada, southwestern Utah, western Arizona and southeastern California come together to migrate southwest to southern California and Baja California. Bats in southeastern Utah, southwestern Colorado, western New Mexico and eastern Arizona travel though western edge of the Sierra Madre Oriental into Jalisco, Sinaloa and Sonora. Some bats that summer in Kansas, Oklahoma, eastern New Mexico and Texas will migrate southward to southern Texas and Mexico. Some bat populations in other areas of North America do not migrate, but are residents and may make seasonal changes in roost sites. While this migration is extremely extensive, there has to be a way that these bats continuously congregate in the same roosts every year. Tadarida brasiliensis have copious amounts of sebaceous glands covering their entire bodies. These glands leave a trace of a lasting scent that other bats are sensitive to. This odor that is left is crucial to marking habitual roosts.
In Austin, Texas, a colony of Mexican free-tailed bats summers (they winter in Mexico) under the Congress Avenue Bridge ten blocks south of the Texas State Capitol. It is the largest urban colony in North America, with an estimated 1,500,000 bats. Each night they eat 10,000 to 30,000 lb (4,500 to 13,600 kg) of insects. Each year they attract 100,000 tourists who come to watch them. In Houston, Texas, a colony is living under the Waugh Street Bridge over Buffalo Bayou. It is the home to 250,000 bats and also attracts viewers. The Mexican free-tailed bat is the official flying mammal of the state of Texas.
Bats ranging eastward from East Texas do not migrate, but local shifts in roost usage often occur seasonally. Also, a regional population that ranges from Oregon to California, has a year-round residence.
Mexican free-tailed bats are primarily insectivores. They hunt their prey using echolocation. The bats eat moths, beetles, dragonflies, flies, true bugs, wasps, and ants. Bats usually catch flying prey in flight. Large numbers of Mexican free-tailed bats fly hundreds of meters above the ground in Texas to feed on migrating insects. The consumption of insects by these bats can be quite significant.
The onset of evening emergence from caves and the end of returns at dawn tend to correlate with sunset and sunrise, respectively, with dawn returns ending increasingly later in correlation to sunrise throughout the summer season. Reproductive females tended to emerge earlier in the evening and return later at dawn in order to gather the extra nutrients they require for reproduction and offspring care. T. brasiliensis bats spend around 60% of their active time foraging while aerial, mostly hunting at heights of 6–15 m (20–49 ft). Individuals will fly 50 km (31 mi) in one night to reach foraging areas. The loose, wrinkled skin around the mouth is thought to aid in expanding the mouth during flight to catch insects. T. brasiliensis requires free water sources to maintain water balance: individuals from the arid environment of New Mexico tend to have thicker renal tissue layers compared to T. brasiliensis from the less arid California, revealing that urine concentrating abilities and water use varies geographically with aridity.
Health and mortality
One individual bat was recorded to have lived eight years, based on dentition. Predators of the bat include large birds such as red-tailed hawk, American kestrels, great horned owls, barn owls, and Mississippi kites. Mammal predators include Virginia opossums, striped skunks, and raccoons. Snakes such as eastern coachwhips and eastern coral snakes may also prey on them, but at a lesser extent. Certain types of beetles prey on neonate and juvenile bats that have fallen to the ground. This species seems to have a low incidence of rabies, at least in the United States. They do, however, contain certain pesticides.
White-nose syndrome (WNS) caused by infection by the fungus P. destructans has increased in prevalence since 2006, mostly affecting species of bats that roost underground such as the little brown bat. The fungus, now suspected to have spread from accidental transportation by human cave workers, is thought to cause frequent arousals during bat hibernation, causing an individual to use fat stores much more quickly and die of starvation before the end of winter. WNS can affect T. brasiliensis, but has yet to be greatly introduced to their habitat due to their preference for more arid caves. WNS has low prevalence in the sub-tropic and tropic regions where T. brasiliensis resides.
Mexican free-tailed bats are nocturnal foragers and begin feeding after dusk. They travel 50 km in a quick, direct flight pattern to feed. This species flies the highest among bats, at altitudes around 3300 m. Bats appear to be most active in late morning and afternoon between June and September. Free-tailed bats are more active in warm weather.
The species has been measured at a ground speed of 160 kilometres per hour (99 mph), measured by an aircraft tracking device. The measurement methodology did not simultaneously record wind speed and ground speed, so the observations could have been affected by strong local gusts, and the bat's maximum air speed remains uncertain.
Guano and ammonia
Among bats that roost in great, concentrated numbers, T. brasiliensis roosts produce large quantities of urine and guano: anywhere from 22 to 99 metric tons per cave and over 18,700 metric tons produced annually. The concentrated large amounts of waste generate high levels of toxic ammonia in the air of a cave. T. brasiliensis individuals have genetic adaptation for withstanding or countering these high levels of ammonia. The bats’ content of CO2 and protein in respiratory mucous and CO2 dissolved in blood plasma increase with increasing levels of dissolved ammonia, providing the bats with a buffer against pH change. This allows the bats to filter out a large majority of inhaled ammonia before it reaches toxic levels in the blood. T. brasiliensis bats are thought to swarm in spiraling motions within caves to ventilate ammonia and renew the air.
Mexican free-tailed bats use echolocation for navigation and detecting prey. Traveling calls are of a brief but constant frequency. However, they switch modulated frequency calls between 40 and 75 kHz if they detect something. Typically, the frequency range of their echolocation is between 49 and 70 kHz, but can be between 25 and 40 kHz if something crosses their path while in flight.
On 6 November 2014, Aaron Corcoran, a biologist at Wake Forest University, North Carolina, reported online in Science that he and his team had detected Mexican free-tailed bats emitting ultrasonic vocalizations which had the effect of jamming the echolocation calls of a rival bat species hunting moths. The ‘jamming’ call led to an increased chance of the rival missing its prey, which the Mexican free-tailed bat was then able to eat itself. Earlier researchers had discovered some 15 types of social calls made by Mexican free-tailed bats and reported that they could adjust their calls to avoid interfering with others in range of their calls.
Mating and reproduction
During the breeding season, females aggregate into maternity roosts. The size of these roosts depends on the environment, with caves having the larger roosts. Mating can occur in an aggressive or passive form. In the aggressive form, the male controls the female's movements, keeping her away from the other bats in the roost. He also tends to vocalize when mating. During passive copulation, the males simply flies to a female in her roost and quietly mounts her with no resistance. This species is a promiscuous breeder and both sexes copulate with multiple partners. Females become sexually mature at about 9 months, while males take even longer, at two years. Females enter estrus once a year, which typically lasts five weeks in the spring. The gestation period of the bat lasts 11–12 weeks, with only one young being born. A number of pups are left in "creches", while their mothers roost elsewhere. The female uses vocalizations and scent to identify her pup. The mother imprints her scent on the young early on. However, young try to steal a suckle from any female that passes through the cluster. A mother will nurse her young daily, and by 4–7 weeks old they are full grown, fully weaned, and independent.
Though abundant and widespread, some local populations have prompted protection and conservation efforts. For instance, during the spring and summer, one of the largest Mexican free-tailed bat populations inhabits Cueva de la Boca, a cave near Monterrey, Mexico. In 2006, the Mexican environmental conservation NGO, Pronatura Noreste, purchased the property. Because of a reduction of more than 95% of the original 20 million bat population, as a result of vandalism, pollution, and uncontrolled tourism, the organization decided to buy the property to place it under conservation. Other species of high ecological value that inhabit the cavern are also being protected.
- Bat bomb, an experimental incendiary weapon that used Mexican free-tailed bats as a dispersal mechanism
- Barquez, R., Diaz, M., Gonzalez, E., Rodriguez, A., Incháustegui, S. & Arroyo-Cabrales, J. (2015). Tadarida brasiliensis. The IUCN Red List of Threatened Species doi:10.2305/IUCN.UK.2015-4.RLTS.T21314A22121621.en
- Ammerman, LK; Lee, DN; Tipps, T (2012). "First molecular insights into the evolution of free-tailed bats in the subfamily Molossinae (Molossidae, Chiroptera)". Journal of Mammalogy. 93 (1): 12–28. doi:10.1644/11-mamm-a-103.1.
- Wilkins, K. (1989). "Tadarida brasiliensis" (PDF). Mammalian Species. 331: 1–10.
- Reid, F. (2006). A field guide to mammals of North America, north of Mexico. 4. Houghton Mifflin Harcourt. p. 136.
- Baker, R. J., Genoways, H. H. (1978). "Zoogeography of Antillean bats", pp. 53–97 in Zoogeography in the Caribbean, F. B. Gill (ed.). Philadelphia: Acad
- Glass BP (1982). "Seasonal movements of Mexican free-tail bats Tadarida brasiliensis mextcana banded in the Great Plains". Southwestern Nat. 27: 127–133. doi:10.2307/3671136.
- Glass, Bryan P. (1982). "Seasonal Movements of Mexican Freetail Bats Tadarida brasiliensis mexicana Banded in the Great Plains". The Southwestern Naturalist. 27 (2): 127–133. doi:10.2307/3671136. JSTOR 3671136.
- "Congress Avenue Bridge". Congress Avenue Bridge Bat Colony. Archived from the original on 12 November 2008.
- "Texas State Symbols". Texas State Library and Archives Commission.
- McWilliams, Lisa A. (2005). "Variation in Diet of the Mexican Free-Tailed Bat (Tadarida brasiliensis mexicana)". Journal of Mammalogy. 86 (3): 599. doi:10.1644/1545-1542(2005)86[599:VIDOTM]2.0.CO;2.
- McCracken, G. F.; Gillam, E. H.; Westbrook, J. K.; Lee, Y. F.; Jensen, M. L.; Balsley, B. B. (2008). "Brazilian free-tailed bats (Tadarida brasiliensis: Molossidae, Chiroptera) at high altitude: Links to migratory insect populations". Integrative and Comparative Biology. 48 (1): 107–18. doi:10.1093/icb/icn033. PMID 21669777.
- Corrigan, Robert. Do Bats Control Mosquitoes? texasmosquito.org
- Animal Fact Sheet: Mexican Free-Tailed Bat. Desert Museum
- Lee, Y. F.; McCracken, G. F. (2001). "Timing and variation in the emergence and return of Mexican free-tailed bats, Tadarida brasiliensis mexicana" (PDF). Zoological Studies. 40 (4): 309–316.
- Bassett, JE (1982). "Habitat aridity and intraspecific differences in the urine concentrating ability of insectivorous bats". Comparative Biochemistry and Physiology. 72 (4): 703–708. doi:10.1016/0300-9629(82)90152-9.
- Gannon, M., A. Kurta, A. Rodriquez-Duran, M. Willig. (2005). Bats of Puerto Rico. Jamaica. The University of the West Indies Press.
- Mikula, P.; Morelli, F.; Lučan, R. K.; Jones, D. N.; Tryjanowski, P. (2016). "Bats as prey of diurnal birds: a global perspective". Mammal Review. 46 (3): 160. doi:10.1111/mam.12060.
- Fenton, B (2012). "Bats and white-nose syndrome". PNAS. 109 (18): 6794–6795. doi:10.1073/pnas.1204793109. PMC .
- Williams, T. C.; Ireland, L. C.; Williams, J. M. (1973). "High Altitude Flights of the Free-Tailed Bat, Tadarida brasiliensis, Observed with Radar". Journal of Mammalogy. 54 (4): 807. doi:10.2307/1379076. JSTOR 1379076.
- Svoboda, P. L.; Choate, J. R. (1987). "Natural History of the Brazilian Free-Tailed Bat in the San Luis Valley of Colorado". Journal of Mammalogy. 68 (2): 224. doi:10.2307/1381461. JSTOR 1381461.
- Allen, L. C.; Turmelle, A. S.; Mendonça, M. T.; Navara, K. J.; Kunz, T. H.; McCracken, G. F. (2009). "Roosting ecology and variation in adaptive and innate immune system function in the Brazilian free-tailed bat (Tadarida brasiliensis)" (PDF). Journal of Comparative Physiology B. 179 (3): 315–23. doi:10.1007/s00360-008-0315-3. PMID 19002470.
- McCracken, Gary F.; Safi, Kamran; Kunz, Thomas H.; Dechmann, Dina K. N.; Swartz, Sharon M.; Wikelski, Martin (9 November 2016). "Airplane tracking documents the fastest flight speeds recorded for bats". Royal Society Open Science. 3 (11): 160398. doi:10.1098/rsos.160398.
- Photopoulos, Julianna (9 November 2016). "Speedy bat flies at 160km/h, smashing bird speed record". New Scientist. Retrieved 11 November 2016.
But not everyone is convinced. Graham Taylor at the University of Oxford says that errors in estimating bat speed by measuring the distance moved between successive positions could be huge. “So I think it would be premature to knock birds off their pedestal as nature's fastest fliers just yet,” he says."These bats are indeed flying very fast at times, but this is based on their ground speed," says Anders Hedenström at the University of Lund in Sweden. "Since they did not measure winds at the place and time where the bats are flying, one can therefore not exclude that the top speeds are not bats flying in a gust."
- Gillam, Erin H.; McCracken, Gary F. (2007). "Variability in the echolocation of Tadarida brasiliensis: Effects of geography and local acoustic environment". Animal Behaviour. 74 (2): 277. doi:10.1016/j.anbehav.2006.12.006.
- Morell, Virginia (6 November 2014). "Holy blocked bat signal! Bats jam each other's calls". new.sciencemag.org. Retrieved 8 November 2014.
- Hogenboom, Melissa (7 November 2014). "Bats sabotage rivals' senses with sound in food race". BBC News. Retrieved 8 November 2014.
- Keeley, Annika T. H.; Keeley, Brian W. (2004). "The Mating System of Tadarida brasiliensis (Chiroptera: Molossidae) in a Large Highway Bridge Colony". Journal of Mammalogy. 85: 113. doi:10.1644/BME-004.
- Loughry, W. J.; McCracken, G. F. (1991). "Factors Influencing Female-Pup Scent Recognition in Mexican Free-Tailed Bats". Journal of Mammalogy. 72 (3): 624. doi:10.2307/1382150. JSTOR 1382150.
- Kunz, Thomas H.; Robson, Simon K. (1995). "Postnatal Growth and Development in the Mexican Free-Tailed Bat (Tadarida brasiliensis mexicana): Birth Size, Growth Rates, and Age Estimation" (PDF). Journal of Mammalogy. 76 (3): 769. doi:10.2307/1382746. JSTOR 1382746.
Data related to Tadarida brasiliensis at Wikispecies
- "Tadarida brasiliensis". Integrated Taxonomic Information System. Retrieved 23 March 2006.
- Bat Conservation International: Mexican free-tailed bats webpage
- Animal Diversity – Tadarida brasiliensis
- ARKive.org: Images/videos of the Brazilian free-tailed bat (Tadarida brasiliensis)
- Washington Post.com: "Mexican Bats Find Cross-Border Benefactors"
- Untamed Science interview with a bat specialist at the Congress Street Bridge Colony
- Bat Conservation International website
- Pronatura Noreste Announces the Purchase of Cueva de la Boca
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(Mexican free-tailed bat). | <urn:uuid:cf2df4e8-60ff-400c-8d71-bb89aed5944c> | 3.734375 | 4,890 | Knowledge Article | Science & Tech. | 61.54935 | 95,508,219 |
Do you really know the importance of parallelization? Does a parallelized code imply a reduction in your execution time? Are all parallelizations equally good? This article talks about these questions and using the calculation of the number pi tries to answer these questions.
Calculation of PI
The code shown below is the calculation of pi by the method of numeric integration. The algorithm has a loop (lines 4-7) which executes a predetermined number of iterations (num_steps) where a reduction over the variable ‘sum’ is done. The variable ‘x’ works like a partial result which has an independent value between iterations. At the end of the loop, the operation between ‘step’ and ‘sum’ produces ‘pi’. The number pi will be more precise if the number of iterations is greater.
The aim of the parallelization is to reduce the variable ‘sum’. The analysis of the code shows that this is a reduction on the variable ‘sum’ and the type is addition. With these features there is more than one way to parallelize this code. We will then see two different types of how to parallelize this code and a comparison between both.
Parallel computation of PI: (1) with CRITICAL; (2) with REDUCTION
The first parallelization is with a critical section on the reduction variable. The reduction variable is shared but it is necessary to protect the access and modification with a critical section. Good practise is to protect the minimum number of operations with the critical section, so the variable ‘aux’ is used to reduce the computation in the critical section.
The second way to parallelize this code is by using the reduction clause. This is a clause provided by the OpenMP standard which abstracts the problem of a reduction. For this clause is only necessary to annotate the reduction variable and the type of reduction, in this case ‘reduction(+:sum)’.
Performance on a multicore machine.
The ideal speed-up is the number of threads, for example if the application is working with 4 threads the ideal speed-up in this case is 4. In the next graph we can see a speed-up comparison between the ideal (red line), the sequential (blue line), the critical (green line) and the parallelization using reduction (yellow line).
The parallelization with the reduction clause is near to obtaining ideal speed-ups, conversely with a parallelization with critical the speed-ups are worse, even the code obtains a slow down. A slow down in a parallelization is something common if we choose a wrong strategy of parallelization. In this case, protecting with a critical is a bad idea because the threads are waiting to enter in the critical section and if the code has a low arithmetic intensity it makes the threads spend more time waiting than executing the code.
In conclusion: Choosing the correct parallelization strategy is really important. A correct decision can change the execution time from ideal times to times that are even worse than the sequential time. Do not miss the next article of our series “OpenMP guided parallelization with Parallware” that will address the parallelization of the matrix-vector product.
The Appentra Team
Learning parallel programming is now faster and easier!
Parallware Trainer is the new interactive, real-time editor with GUI features to facilitate the learning, usage, and implementation of parallel programming.
Users are actively involved in learning parallel programming through observation, comparison, and hands-on experimentation.Parallware Trainer provides support for widely used parallel programming strategies using OpenMP and OpenACC with execution on multicore processors and GPUs. | <urn:uuid:15e37626-477b-4226-9b08-86be26213e87> | 3.53125 | 762 | Documentation | Software Dev. | 32.885084 | 95,508,236 |
An novel method that could add texture to other worlds.
Transiting exoplanets generally orbit in the same plane, so how is this planet so misaligned in this multi-planet system?
Globular clusters in the Milky Way are shedding their stars. How can we tell when this process began?
It has long been theorized that exoplanet atmospheres should be partially composed of helium — now we finally have our first detection in the atmosphere of Wasp-107b. Today’s bite explains how the authors observed helium and discuss what this means for the atmosphere of this planet.
Today’s bite looks at how the ratio of various elements can inform our view of what happens during a supernova.
Most of the known exoplanets resemble “hot Jupiters” because they’re bigger and easier to find. But how can we find Earth-like planets? Check out Dr. Debra Fischer’s plenary talk at #AAS232 to learn more about the “Past, Present, and Future” of exoplanet science. | <urn:uuid:409e9492-ee53-491d-a885-5961ab276722> | 3.171875 | 226 | Content Listing | Science & Tech. | 56.631263 | 95,508,252 |
- Open Access
Leaner and meaner genomes in Escherichia coli
© BioMed Central Ltd 2006
Published: 24 October 2006
A 'better' Escherichia coli K-12 genome has recently been engineered in which about 15% of the genome has been removed by planned deletions. Comparison with related bacterial genomes that have undergone a natural reduction in size suggests that there is plenty of scope for yet more deletions.
Why should one want to design a better bacterium? One answer is that this is one way of really testing our understanding of how a living cell works - by making predictions, manipulating the object, and seeing what we get. This is the province of synthetic biology, whose ultimate goal is to understand life by constructing it from scratch; it is hoped that along the way will emerge an understanding of the properties of living cells and organisms that is difficult to arrive at by conventional investigation of the organisms themselves [1, 2]. Much progress has been made recently towards designing and synthesizing novel biological organisms from a set of standardized parts , such as protein-coding genes, regulators, and terminators, as listed on the BioBrick website .
In contrast, in work recently published in Science, Posfai et al. have taken a 'deconstructionist' approach to redesigning life. Specific regions of the Escherichia coli K-12 genome were targeted for deletion with the intention of improving the production potential of this model organism. As an unanticipated side effect, they have come up with a bacterium that is even better than the parental strain for some purposes, in that it is more efficiently electroporated and accurately propagates unstable recombinant genes and plasmids. It is interesting to compare these engineered reduced genomes with the genomes of other bacteria within the Enterobacteriaceae, some of which are endosymbionts whose genomes have become dramatically reduced during evolution.
Smaller is indeed often better, as people who travel frequently or who worry about buying fuel for their cars know. Posfai et al. chose which genes and genomic regions to remove on the basis of several criteria, including "troublesome sequences" such as insertion sequence (IS) sites and transposable elements that appear to code only for their own replication, and repeat regions that can cause homologous recombination. They also removed some regions that are not present in all E. coli genomes, and so are unlikely to be essential for basic properties such as growth. There are many large regions throughout the E. coli K-12 genome that are not conserved among other E. coli genomes, but given the variation in genome size between different strains, with differences of more than 1 million base pairs (20% of the genome) being common, this is perhaps not surprising.
To make the deletions, synthetic oligomers containing regions homologous to target sites flanking the desired region were used. Regions were deleted by recombination mediated by the phage lambda Red system, and done in a way that gave 'scarless' deletions where no marker sequence was left. The strains with deletions were then tested for growth in minimal media. Finally, as one last step to check for quality, the reduced strains were hybridized to tiling microarrays of the E. coli K-12 genome. The first reduced strain yielded surprising results. In the words of the authors: "Alarmingly, we found five unexpected copies of IS that had transposed to new locations since the project began in 2002." Thus new strains were made, which were shown to be free of IS elements. The engineered strains had similar growth rates to their parent strain, and the electroporation efficiency of engineered strain MDS42 was 100 times greater than for the original E. coli MG1655 K-12. Furthermore, plasmid genes that were unstable in MG1655 were found to be completely stable in the engineered strains. IS mutagenesis is a natural defense against deleterious genes, and is normally helpful to bacteria in the wild, but is detrimental when one wishes to grow these genes in laboratory strains of E. coli.
Natural genome reduction
List of currently sequenced genomes from the family Enterobacteriaceae of the γ-Proteobacteria
Number of proteins
Genome size (bp)
Number of tRNA genes
Number of rRNA genes
Escherichia coli CFT073
Escherichia coli O157 RIMD
Escherichia coli O157 EDL
Escherichia coli UTI89
Escherichia coli strain 536
Salmonella enterica CT18
Salmonella typhimurium LT2
Salmonella enterica SCB67
Shigella flexneri 2a301
Escherichia coli K-12 W3110
Escherichia coli K-12 MG1655
Salmonella enterica Ty2
Shigella dysenteriae Sd197
Shigella sonnei Ss046
Yersinia pestis Antiqua
Shigella boydii Sb227
Shigella flexneri 5str8401
Salmonella enterica ATCC9150
Yersinia pestis KIM
Shigella flexneri 2457T
Escherichia coli MDS12
Yersinia pestis CO-92
Yersinia pestis Nepal516
Yersinia pseudotuber IP32953
Yersinia pestis Mediaevails
Escherichia coli MDS41
Escherichia coli MDS42
Escherichia coli MDS43
Buchnera aphidicola APS
Buchnera aphidicola Sg
Buchnera aphidicola BBp
The B. cicadellinicola genome is towards the bottom of the table, but there are four known genomes in this family that encode an even smaller number of proteins. The genome at the bottom of the list (Buchnera aphidicola strain BBp) codes for only 504 proteins, or less than 10% of the number of proteins encoded by the larger E. coli genomes (5,379 proteins in E. coli CFT073). The smallest 'normal', free-living enterobacter (apart from the newly engineered E. coli genomes) is a Yersinia pestis strain (Mediaevalis), with 3,895 genes, or only 72% of the number of genes found in the largest enterobacterial genome. Furthermore, only slightly more than half of the Y. pestis Mediaevalis genes have homologs in the CFT073 genome (52% - that is, 2,938 Y. pestis genes/5,379 E. coli CFT073 genes). Thus, just on the basis of gene diversity within the enteric bacteria, it seems that perhaps half or more of the genes in the larger enterobacterial genomes might be expendable - at least under laboratory growth conditions. Indeed, only 620 E. coli K-12 genes have been found experimentally to be essential for growth in rich media, while 3,126 genes were found to be dispensable for growth under this condition . This indicates that there could well be more room for engineered deletions in the E. coli genomes.
The reduced genomes are shown in the inner circles. B. aphidicola strain BBp is the smallest genome, and is depicted as the orange inner circle, which has few hits, as expected, as this genome encodes so few proteins. The B. cicadellinicola genome is the next circle (red), and the third is Sodalis glossinidius, which is a genome that is undergoing reduction, but still contains about 2,500 genes, as well as about 1,000 pseudogenes . This circle contains more hits, although it is still a bit sparse compared to the inner three circles, which have large regions where nearly all of the proteins are conserved.
These reduced genomes contain only about 10% of the genes in the larger E. coli genomes from which they originated long ago. This raises many questions. What about the remaining 90%? Does E. coli really not need most of these genes? Some are certainly redundant - a necessary condition for robust systems - and the definition of 'essential genes' might include some genes that do not give a lethal phenotype when deleted .
Is it possible to model which genes would remain, and which 90% or so could be removed, under the right conditions? A model of E. coli metabolism was recently used to generate reduced genomes in silico , and to compare these genomes with the endosymbiotic genomes shown at the bottom of Table 1. The idea was to use a known metabolic environment and then to model random gene loss, and evaluate relative viability. If the gene loss had no apparent effect, then another gene would be removed, and this process was repeated until a minimal genome was obtained.
Two different endosymbiotic bacterial environments were modeled - those of Buchnera and Wiggelsworthia - and the model predicted the gene content of the two genomes to about 80% accuracy .
There are, of course, several different ways to arrive at the same reduced genome, but by looking at which genes are necessary to perform core metabolic activities (for a given endosymbiotic environment, it should be stressed), it is possible in general to predict the genes that are likely to remain in a reduced genome. This information can then be used in future experiments to design better genomes, tailor-made for specific applications. Posfai et al. were not intending to manufacture a 'minimal genome' such as the highly reduced ones discussed here, but rather they simply wanted to engineer an E. coli genome that would be a better 'workhorse' - that is, it would be easier to get DNA into the cells, and the DNA and its gene products would be stable once it was there. There are others, however, who do have the aim of using synthetic biology to design and manufacture a minimal genome . Perhaps the time is near when mircobiology will join the engineering sciences.
I would like to thank Michael Sismour for useful comments about synthetic biology and the Danish Center for Scientific Computing for funding.
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Organic nitrogen components in soils from southeast China
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To investigate the amounts of extractable organic nitrogen (EON), and the relationships between EON and total extractable nitrogen (TEN), especially the amino acids (AAs) adsorbed by soils, and a series of other hydrolyzed soil nitrogen indices in typical land use soil types from southeast China. Under traditional agricultural planting conditions, the functions of EON, especially AAs in the rhizosphere and in bulk soil zones were also investigated.
Pot experiments were conducted using plants of pakchoi (Brassica chinensis L.) and rice (Oryza sativa L.). In the rhizosphere and bulk soil zone studies, organic nitrogen components were extracted with either distilled water, 0.5 mol/L K2SO4 or acid hydrolysis.
K2SO4-EON constituted more than 30% of TEN pools. K2SO4-extractable AAs accounted for 25% of EON pools and nearly 10% of TEN pools in rhizosphere soils. Overall, both K2SO4-EON and extractable AAs contents had positive correlations with TEN pools.
EON represented a major component of TEN pools in garden and paddy soils under traditional planting conditions. Although only a small proportion of the EON was present in the form of water-extractable and K2SO4-extractable AAs, the release of AAs from soil exchangeable sites might be an important source of organic nitrogen (N) for plant growth. Our findings suggest that the content of most organic forms of N was significantly greater in rhizosphere than in bulk soil zone samples. However, it was also apparent that the TEN pool content was lower in rhizosphere than in bulk soil samples without added N.
Key wordsExtractable organic nitrogen Amino acids Rhizosphere Bulk soil
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Question: Have human beings stopped evolving? Will humans look any different in the future? (Submitted by Kiran Uttarkar)
Michio Kaku: Kiran, if you read science fiction you might think that humans in the future will be slender, short, bald, with big heads and big eyes that sort of the stereotype that you get from the comic books. However, you have to realize that as far a gross evolutionary pressure is concerned; there is none anymore on the human race. For example, in the old days, when we lived in the forests, there was enormous selection and pressures placed on us to develop a large brain, to understand how to use tools, to run, to be able to navigate, to survive in the forests. Enormous pressures on us because if you were not fit to live in the forest, you died. And so your genes are not here today.
But how much evolutionary pressure is being placed on us today? Well, first of all, there are no more Australias. Australia is a content that broke off from the other continents and it evolved very rapidly because it diverged from the rest of the evolutionary tree. There are no more Australias anymore.
In the sense, we have jet airplanes. You can jet airplane… you can go pretty much anywhere on the planet earth, meet people, have children and your genes are now spread throughout the planet earth. We no longer have any isolated pockets, like Australia, which would accelerate human evolution. Now, evolution is still taking place, it takes place every time two people mate. It takes place inside our bodies, in our immune systems, in our body chemistry. Evolution is still taking place. But gross evolution, that is, evolution that will give us big brains, big eyes, bald heads and little bodies, that kind of gross evolution is pretty much gone.
Now, that doesn’t mean that we can’t have genetic engineering. That’s many decades away. At the present time, we can only manipulate perhaps one gene at a time. It is a very painful process, we cannot, for example, create a pig with wings, that would require thousands of genes being manipulated. And we simply don’t have that technology. We only manipulate one gene at a time.
So I think we are many, many decades away from being able to actually influence human evolution. So in other words, chances are, decades from now, we’ll look pretty much the same. | <urn:uuid:916f7637-91cd-4477-a420-4f55cab3bf01> | 2.96875 | 511 | Audio Transcript | Science & Tech. | 49.575554 | 95,508,300 |
A deficiency of oxygen and the heavy metal molybdenum in the ancient deep ocean may have delayed the evolution of animal life on Earth by nearly two billion years, a study led by UC Riverside biogeochemists has found.
The researchers arrived at their result by tracking molybdenum in black shales, which are a kind of sedimentary rock rich in organic matter and usually found in the deep ocean. Molybdenum is a key micronutrient for life and serves as a proxy for oceanic and atmospheric oxygen amounts.
Study results appear in the March 27 issue of Nature.
Following the initial rise of oxygen in the Earth’s atmosphere 2.4 billion years ago, oxygen was transferred to the surface ocean to support oxygen-demanding microorganims. Yet the diversity of these single-celled life forms remained low, and their multicellular ancestors, the animals, did not appear until about 600 million years ago, explained Timothy Lyons, a professor of biogeochemistry in the Department of Earth Sciences and one of the study’s authors.
Suspecting that deficiencies in oxygen and molybdenum might explain this evolutionary lag, Lyons and his colleagues measured abundances of molybdenum in ancient marine sediments over time to estimate how much of the metal had been dissolved in the seawater in which the sediments formed.
The researchers found significant, firsthand evidence for a molybdenum-depleted ocean relative to the high levels measured in modern, oxygen-rich seawater.
“These molybdenum depletions may have retarded the development of complex life such as animals for almost two billion years of Earth history,” Lyons said. “The amount of molybdenum in the ocean probably played a major role in the development of early life. As in the case of iron today, molybdenum can be thought of as a life-affirming micronutrient that regulates the biological cycling of nitrogen in the ocean.
“At the same time, molybdenum’s low abundance in the early ocean tracks the global extent of oxygen-poor seawater and implies that the amount of oxygen in the atmosphere was still low.
“Knowing the amount of oxygen in the early ocean is important for many reasons, including a refined understanding of how and when appreciable oxygen first began to accumulate in the atmosphere,” Lyons said. “These steps in oxygenation are what gave rise ultimately to the first animals almost 600 million years ago – just the last tenth or so of Earth history.”
For animal life to commence, survive and eventually expand on Earth, a threshold amount of oxygen – estimated to be on the order of 1 to 10 percent of present atmospheric levels of oxygen – was needed.
Past research has shown that Earth’s oxygenation occurred in two major steps:
The first step, around 2.4 billion years ago, took place as the ocean transitioned to a state where only the surface ocean was oxygenated by photosynthesizing bacteria, while the deep ocean was relatively oxygen-free.
The second step, around 600 million years ago, marked the occasion when the entire ocean became fully oxygenated through a process not yet fully understood.
“We wanted to know what the state of the ocean was between the two steps,” said Clinton Scott, a graduate student working in Lyons’s lab and the first author of the research paper. “By tracking molybdenum in shales rich in organic matter, we found the deep ocean remained oxygen- and molybdenum-deficient after the first step. This condition may have had a negative impact on the evolution of early eukaryotes, our single-celled ancestors. The molybdenum record also tells us that the deep ocean was already fully oxygenated by around 550 million years ago.”
According to Scott, the timing of the oxygenation steps suggests that significant events in Earth history are related. Scientists have long speculated that the evolution of the first animals was linked somehow to the so-called Snowball Earth hypothesis, which posits that the Earth was covered from pole to pole in a thick sheet of ice for millions of years at a time. “The second oxygenation step took place not long after the last Snowball Earth episode ended around 600 million years ago,” Scott said. “So one question is: Did this global glaciation play a role in the increasing abundance of oxygen which, in turn, enabled the evolution of animals?”
Scott and Lyons were joined in the research by A. Bekker of the Carnegie Institution of Washington, DC; Y. Shen of the Université du Québec à Montréal, Canada; S.W. Poulton of Newcastle University, Newcastle upon Tyne, United Kingdom; X. Chu of the Chinese Academy of Sciences, Beijing, China; and A.D. Anbar of Arizona State University, Tempe, Ariz.
The research was supported by grants from the U.S. National Science Foundation Division of Earth Sciences and the NASA Astrobiology Institute.
More about molybdenum as a proxy for ocean chemistry
Molybdenum, a metal abundant in the ocean today but less so at times in the past, is an excellent tracer of ancient chemistry for two reasons. First, the primary source of molybdenum to the ocean is oxidative weathering of continental crust, requiring oxygen in the atmosphere. Second, molybdenum is removed primarily in marine sediments where oxygen is absent and sulfide is abundant. Thus the enrichment of molybdenum in ancient organic-rich shales requires oxygen in the atmosphere but high sulfur and very low or no oxygen in the deep ocean. This combination is relatively rare today but may have been common when oxygen was less abundant in the earlier atmosphere.
When oxygen is available in the atmosphere, the amount of dissolved molybdenum in seawater is determined by the extent of hydrogen-sulfide-containing sediments and bottom waters (the colder, more isolated, lowermost layer of ocean water). Where sulfidic environments are widespread, the pool of molybdenum remaining in seawater is small, growing as the sulfidic environments shrink. The amount of molybdenum in the seawater is reflected in the magnitude of molybdenum enrichment in shales deposited in the deep ocean.
The UCR-led team of researchers estimated the size of the oceanic reservoir, and thus the extent of sulfidic bottom waters and sediments, based on the concentration of molybdenum in ancient black shales. They did so by dissolving the samples in a cocktail of acids and analyzing the dissolved rock for concentration using a mass spectrometer. The amount of this metal in the shales tracks the oxygen state of the early ocean and atmosphere and also points to the varying abundance of this essential ingredient of life. Molybdenum limitations may have delayed the development of eukaryotes, including the first animals, our earliest multicellular cousins.
The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment of about 17,000 is projected to grow to 21,000 students by 2010. The campus is planning a medical school and already has reached the heart of the Coachella Valley by way of the UCR Palm Desert Graduate Center. With an annual statewide economic impact of nearly $1 billion, UCR is actively shaping the region's future. To learn more, visit www.ucr.edu or call (951) UCR-NEWS.
Iqbal Pittalwala | EurekAlert!
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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May 06, 2017 08:27 AM EDT
Researchers associated with the Continuous Electron Beam Accelerator Facility at the U.S. Department of Energy's Thomas Jefferson National Accelerator Facility have taken the first experimental result toward solving the problem of quark confinement. Their research aims to study hybrid mesons, which resembles to ordinary mesons in composition, but these unstable subatomic particles are said to exhibit drastically different behavior.
The first experimental result of the researchers has been published from the newly upgraded CEBAF at the Department of Energy's Thomas Jefferson National Accelerator Facility. The result clearly shows the feasibility of finding out a potential new form of matter to have a detailed investigation on why quarks are never detected in isolation.
The professor of physics at Carnegie Mellon University (CMU) and spokesperson for the Gluonic Excitations Experiment (GlueX) at Jefferson Lab, Curtis Meyer, made it known that a meson is a quark and antiquark bound together, and people's understanding is that the glue holds it together. While a hybrid meson is a strong gluonic field being excited, Jefferson Lab reported.
Meyer claims that generating hybrid mesons will help nuclear physicists to have a detailed analysis on particles in which the strong gluonic field will contribute directly to their properties. The hybrid mesons could provide an opening into how subatomic particles are created by the strong force and quark confinement, Phys.Org reported.
Meyer hopes that they can demonstrate the excited gluonic field as an essential constituent of matter. That is something that has not been studied in anything that they have seen so far. Thus, it could be a new type of hadronic matter that has not been perceived.
Furthermore, Meyer said that he is sure that they have produced hybrid mesons already, they just don't have enough data to start searching for mesons. Meyer also said that there are several steps that they are going through in terms of understanding their analysis and the detector.
Meanwhile, Watch The Video Here:
See Now: Facebook will use AI to detect users with suicidal thoughts and prevent suicide© 2017 University Herald, All rights reserved. Do not reproduce without permission. | <urn:uuid:c7b056cd-90a1-47cf-ae40-59e02ea00540> | 2.875 | 445 | News Article | Science & Tech. | 34.02 | 95,508,307 |
Astrolecture Series: Unveiling the Dark Universe | The Presidio
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What is “dark matter?” This is a question that has preoccupied astrophysicists for many decades. Observations show that 80% of the matter in our universe is in this mysterious, invisible form. In this talk, Dr. Yashar Hezaveh, a Hubble Fellow at the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University, discusses how ALMA, the world’s most sophisticated radio telescope, is used to observe some of the most distant galaxies of our universe to learn new things about dark matter.
On their 12 billion light year journey to us, light rays from these galaxies pass near other galaxies. As this happens, the dark matter halos of the intervening galaxies, large and small, bend their trajectories, causing the images here on the Earth to look distorted, like images in a funhouse mirror.
Learn more about our strange and terrifyingly wide universe at this event. Free but an RSVP is required. | <urn:uuid:91ae1bb3-b432-41dd-b774-c87575c4155f> | 2.78125 | 265 | News (Org.) | Science & Tech. | 40.80777 | 95,508,321 |
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When oil started gushing into the Gulf of Mexico in late April 2010, friends asked George Haller whether he was tracking its movement. That's because the McGill engineering professor has been working for years on ways to better understand patterns in the seemingly chaotic motion of oceans and air. Meanwhile, colleagues of Josefina Olascoaga in Miami were asking the geophysicist a similar question. Fortunately, she was.
For those involved in managing the fallout from environmental disasters like the Deepwater Horizon oil spill, it is essential to have tools that predict how the oil will move, so that they make the best possible use of resources to control the spill. Thanks to work done by Haller and Olascoaga, such tools now appear to be within reach. Olascoaga's computational techniques and Haller's theory for predicting the movement of oil in water are equally applicable to the spread of ash in the air, following a volcanic explosion.
"In complex systems such as oceans and the atmosphere, there are a lot of features that we can't understand offhand," Haller explains. "People used to attribute these to randomness or chaos. But it turns out, when you look at data sets, you can find hidden patterns in the way that the air and water move." Over the past decade, the team has developed mathematical methods to describe these hidden structures that are now broadly called Lagrangian Coherent Structures (LCSs), after the French mathematician Joseph-Louis Lagrange.
"Everyone knows about the Gulf Stream, and about the winds that blow from the West to the East in Canada," says Haller, "but within these larger movements of air or water, there are intriguing local patterns that guide individual particle motion." Olascoaga adds, "Though invisible, if you can imagine standing in a lake or ocean with one foot in warm water and the other in the colder water right beside it, then you have experienced an LCS running somewhere between your feet."
"Ocean flow is like a busy city with a network of roads," Haller says, "except that roads in the ocean are invisible, in motion, and transient." The method Haller and Olascoaga have developed allows them to detect the cores of LCSs. In the complex network of ocean flows, these are the equivalent of "traffic intersections" and they are crucial to understanding how the oil in a spill will move. These intersections unite incoming flow from opposite directions and eject the resulting mass of water. When such an LCS core emerges and builds momentum inside the spill, we know that oil is bound to seep out within the next four to six days. This means that the researchers are now able to forecast dramatic changes in pollution patterns that have previously been considered unpredictable.
So, although Haller wasn't tracking the spread of oil during the Deepwater Horizon disaster, he and Olascoaga were able to join forces to develop a method that does not simply track: it actually forecasts major changes in the way that oil spills will move. The two researchers are confident that this new mathematical method will help those engaged in trying to control pollution make well-informed decisions about what to do.
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
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An important web application configuration task is to create the path by which your servlet is requested by web users. This is what the user types into the address field of his browser in order to make a request to the servlet. While this is sometimes the full name of the servlet, that convention often results in an awkward URI. For example, a web site might have a servlet that dynamically assembles a "Resources" page, instead of a static resources.html page. Using the full servlet name, the request URL might be http://www.myorganization.com/servlet/com.organization.servlets.resources.ResourceServlet. This is quite a path to type in; it makes much more sense to map this to a servlet path, which is an alias for the servlet. Using the servlet path, the (new) address for the dynamic page might be http://www.myorganization.com/resources. The servlet path, in this case, is /resources.
This servlet path is also the identifier used by
other servlets or JSPs that forward
requests to this particular servlet, as
well as the address that an HTML form
tag uses in its
attribute to launch parameter names and
values toward the servlet. The servlet
specification offers an intuitive and
flexible way to map HTTP requests to
servlets in the
This chapter describes how you can use the web.xml deployment descriptor to create one or more aliases (servlet paths) to your servlet. It also discusses how to invoke the servlet ... | <urn:uuid:5ee8f7d4-7514-4c19-b1d7-796bdb1e8f8f> | 3.234375 | 333 | Documentation | Software Dev. | 60.13745 | 95,508,365 |
Reentrant is an adjective that describes a computer program or routine that is written so that the same copy in memory can be shared by multiple users. Reentrant code is commonly required in operating systems and in applications intended to be shared in multi-use systems. A programmer writes a reentrant program by making sure that no instructions modify the contents of variable values in other instructions within the program. Each time the program is entered for a user, a data area is obtained in which to keep all the variable values for that user. The data area is in another part of memory from the program itself. When the program is interrupted to give another user a turn to use the program, information about the data area associated with that user is saved. When the interrupted user of the program is once again given control of the program, information in the saved data area is recovered and the program can be reentered without concern that the previous user has changed some instruction within the program. | <urn:uuid:fa7a242a-bd43-4e02-b25a-f48e2790526c> | 3.6875 | 195 | Knowledge Article | Software Dev. | 32.784318 | 95,508,367 |
MADISON - New isotopic analyses of the meteorite that provided hints of past life on Mars reveals a low-temperature origin, boosting the idea that features of the meteorite may have been formed by living organisms.
The study, published today (March 14) in the journal Science by a team led by University of Wisconsin-Madison geochemist John W. Valley, lends powerful new support to the notion that the carbonate globules found within the meteorite, dubbed ALH84001, were formed on the Red Planet under conditions consistent with life.
The isotopic procedures employed by Valley and his colleagues were developed specifically for the Mars rock. Results contradict claims that the carbonate globules found in the rock were formed at blistering temperatures too hot to support life, or were formed on Earth, two primary arguments advanced against the meteorite as evidence of past life on Mars.
"Everything we see is consistent with biological activity, but I still wouldn't rule out low-temperature inorganic processes as an alternative explanation" said Valley. "We have not proven that this represents life on Mars, but we have disproven the high-temperature hypothesis."
Valley said the high-temperature origin hypothesis relies on a set of thermodynamic assumptions that don't measure up on Earth, and therefore don't apply to an ancient Mars that may have had conditions more conducive to life.
"If the same assumptions are applied to the carbonates found in the Earth's oceans, one would erroneously conclude that the water temperatures are over 1,000 degrees Fahrenheit and the surface pressures are several thousand atmospheres," Valley said.
"These carbonates in the meteorite are easily explained by low-temperature processes similar to those commonly found on Earth," he said.
The meteorite at the center of the scientific controversy was blasted off the surface of Mars about 15 million years ago and fell to Earth about 13,000 years ago.
There is also widespread agreement that the rock is very old, probably 4.5 billion years, and that it formed in the Martian crust. The age of the rock sparked interest, because it formed at a time when the Red Planet was warmer, wetter and potentially more hospitable to life.
The new study was conducted by a team that includes Valley, John M. Eiler and Edward M. Stolper of the California Institute of Technology, Colin M. Graham of the University of Edinburgh, Everett K. Gibson of NASA's Johnson Space Center, and Christopher S. Romanek of the University of Georgia.
The analysis was made with a device designed to analyze minute samples of material gleaned from spots less than one-quarter of the diameter of a human hair. Known as an ion microprobe, it uses a beam of high-energy plasma to burn tiny craters on the surface of a sample, in this case a polished sample no bigger than a grain of rice. The vaporized material is held in a vacuum and drawn into a mass spectrometer for isotopic analysis.
The advantage of the ion microprobe, said Valley, is that it allows for minuscule amounts of material to be sampled, one million times less than would typically be necessary. Employing the microprobe, Valley and his colleagues were able to look deep within the carbonates themselves and make the first in situ measurements of the controversial globules.
"Making these analyses in situ has never been done before," he said. "For the first time, we can actually see what we analyze."
He described the carbonates as "pancakes within pancakes" having a distinct chemistry in each. "We can go in and look for differences or similarities within the carbonates themselves."
"Without the ion microprobe, one doesn't really know what's being analyzed. We found that the globules are different. There is a very intricate concentric mineral, chemical and isotopic zonation (within the globules)."
Valley's team measured the ratios of two different isotopic species of oxygen and two of carbon. They found that the carbon ratios in the meteorite are high, higher than in Earthbound rocks.
"This rules out the idea that these features formed while the meteorite was lodged in the Antarctic ice," said Valley. "Such ratios have never been measured in a terrestrial sample."
Oxygen isotope ratios are also high, Valley said, but he noted that the significant discovery is that the oxygen isotopes are not evenly distributed within the sample. "The ion microprobe allows us to determine which parts of the meteorite have more of a particular oxygen isotope."
The life on Mars hypothesis has been challenged on the grounds that the carbonates formed in chemical equilibrium above 1200 degrees Fahrenheit. The new data prove that the meteorite is not in isotopic or chemical equilibrium.
"There is no self-consistent evidence to suggest such a high-temperature genesis," said Valley. "All of the chemical, mineralogical and isotopic evidence that we present is consistent with a low-temperature origin."
The upshot of the analysis is that the carbonates most likely precipitated at temperatures below 200 degrees Fahrenheit, under conditions hospitable to some forms of microscopic life.
- Terry Devitt, (608) 262-8282, email@example.com | <urn:uuid:19055f01-b5d6-4730-964a-295141819699> | 3.078125 | 1,093 | News Article | Science & Tech. | 32.498877 | 95,508,376 |
Description - The Magnetotelluric Method by Alan D. Chave
The magnetotelluric method is a technique for imaging the electrical conductivity and structure of the Earth, from the near surface down to the 410 km transition zone and beyond. This book forms the first comprehensive overview of magnetotellurics, from the salient physics and its mathematical representation to practical implementation in the field, data processing, modeling and geological interpretation. Electromagnetic induction in 1-D, 2-D and 3-D media is explored, building from first principles, and with thorough coverage of the practical techniques of time series processing, distortion, numerical modeling and inversion. The fundamental principles are illustrated with a series of case histories describing geological applications. Technical issues, instrumentation and field practices are described for both land and marine surveys. This book provides a rigorous introduction to magnetotellurics for academic researchers and advanced students, and will be of interest to industrial practitioners and geoscientists wanting to incorporate rock conductivity into their interpretations.
Buy The Magnetotelluric Method by Alan D. Chave from Australia's Online Independent Bookstore, Boomerang Books.
(247mm x 174mm x 31mm)
Cambridge University Press
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- 220.127.116.11 The Subquery as Scalar Operand
- 18.104.22.168 Comparisons Using Subqueries
- 22.214.171.124 Subqueries with ANY, IN, or SOME
- 126.96.36.199 Subqueries with ALL
- 188.8.131.52 Row Subqueries
- 184.108.40.206 Subqueries with EXISTS or NOT EXISTS
- 220.127.116.11 Correlated Subqueries
- 18.104.22.168 Derived Tables
- 22.214.171.124 Subquery Errors
- 126.96.36.199 Optimizing Subqueries
- 188.8.131.52 Rewriting Subqueries as Joins
A subquery is a
within another statement.
All subquery forms and operations that the SQL standard requires are supported, as well as a few features that are MySQL-specific.
Here is an example of a subquery:
SELECT * FROM t1 WHERE column1 = (SELECT column1 FROM t2);
In this example,
SELECT * FROM t1 ... is the
outer query (or outer
(SELECT column1 FROM
t2) is the subquery. We say that
the subquery is nested within the outer
query, and in fact it is possible to nest subqueries within other
subqueries, to a considerable depth. A subquery must always appear
The main advantages of subqueries are:
They allow queries that are structured so that it is possible to isolate each part of a statement.
They provide alternative ways to perform operations that would otherwise require complex joins and unions.
Many people find subqueries more readable than complex joins or unions. Indeed, it was the innovation of subqueries that gave people the original idea of calling the early SQL “Structured Query Language.”
Here is an example statement that shows the major points about subquery syntax as specified by the SQL standard and supported in MySQL:
DELETE FROM t1 WHERE s11 > ANY (SELECT COUNT(*) /* no hint */ FROM t2 WHERE NOT EXISTS (SELECT * FROM t3 WHERE ROW(5*t2.s1,77)= (SELECT 50,11*s1 FROM t4 UNION SELECT 50,77 FROM (SELECT * FROM t5) AS t5)));
A subquery can return a scalar (a single value), a single row, a single column, or a table (one or more rows of one or more columns). These are called scalar, column, row, and table subqueries. Subqueries that return a particular kind of result often can be used only in certain contexts, as described in the following sections.
There are few restrictions on the type of statements in which
subqueries can be used. A subquery can contain many of the
keywords or clauses that an ordinary
SELECT can contain:
comments, functions, and so on.
In MySQL, you cannot modify a table and select from the same table
in a subquery. This applies to statements such as
UPDATE, and (because subqueries can
be used in the
For information about how the optimizer handles subqueries, see Section 8.2.2, “Subquery Optimization”. For a discussion of restrictions on subquery use, including performance issues for certain forms of subquery syntax, see Section C.4, “Restrictions on Subqueries”. | <urn:uuid:a5e931d8-3f6b-4c84-9a04-3273bccfccc4> | 2.609375 | 750 | Documentation | Software Dev. | 69.45552 | 95,508,392 |
Venus is blanketed in sulphuric acid clouds that block our view of the surface. The clouds form at altitudes of 50–70 km when sulphur dioxide from volcanoes combines with water vapour to make sulphuric acid droplets. Any remaining sulphur dioxide should be destroyed rapidly by the intense solar radiation above 70 km.
So the detection of a sulphur dioxide layer at 90–110 km by ESA’s Venus Express orbiter in 2008 posed a complete mystery. Where did that sulphur dioxide come from?
Now, computer simulations by Xi Zhang, California Institute of Technology, USA, and colleagues from America, France and Taiwan show that some sulphuric acid droplets may evaporate at high altitude, freeing gaseous sulphuric acid that is then broken apart by sunlight, releasing sulphur dioxide gas.
“We had not expected the high-altitude sulphur layer, but now we can explain our measurements,” says Håkan Svedhem, ESA’s Venus Express Project Scientist.
“However, the new findings also mean that the atmospheric sulphur cycle is more complicated than we thought.”
As well as adding to our knowledge of Venus, this new understanding may be warning us that proposed ways of mitigating climate change on Earth may not be as effective as originally thought.
However, the new work on the evaporation of sulphuric acid on Venus suggests that such attempts at cooling our planet may not be as successful as first thought, because we do not know how quickly the initially protective haze will be converted back into gaseous sulphuric acid: this is transparent and so allows all the Sun’s rays through.
“We must study in great detail the potential consequences of such an artificial sulphur layer in the atmosphere of Earth,” says Jean-Loup Bertaux, Université de Versailles-Saint-Quentin, France, Principal Investigator of the SPICAV sensor on Venus Express. “Venus has an enormous layer of such droplets, so anything that we learn about those clouds is likely to be relevant to any geo-engineering of our own planet.”
In effect, nature is doing the experiment for us and Venus Express allows us to learn the lessons before experimenting with our own world.
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
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13.07.2018 | Event News
12.07.2018 | Event News
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20.07.2018 | Power and Electrical Engineering
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20.07.2018 | Materials Sciences | <urn:uuid:85a8048a-f249-4ebb-b535-2edd9060e26a> | 4.375 | 1,045 | Content Listing | Science & Tech. | 40.787672 | 95,508,395 |
|Scientific Name:||Hippocampus reidi Ginsburg, 1933|
Hippocampus obtusus Ginsburg, 1933
Hippocampus poeyi Howell and Riviero, 1934
|Taxonomic Source(s):||Lourie, S.A., Pollom, R.A. and Foster, S.J. 2016. A global revision of the seahorses Hippocampus Rafinesque 1810 (Actinopterygii: Syngnathiformes): Taxonomy and biogeography with recommendations for future research. Zootaxa 4146(1): 1-66.|
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Assessor(s):||Oliveira, T. & Pollom, R.|
Hippocampus reidi is a coastal seahorse species that inhabits corals, seagrasses, estuaries, and especially macroalgae and mangroves from North Carolina, throughout the Gulf of Mexico and Caribbean Sea, to southern Brazil. The species is threatened by the loss and degradation of some of its preferred habitats, particularly mangroves, due to coastal development. It is particularly threatened by being caught as bycatch in trawl and artisanal fisheries (and subsequently used for curios, religious amulets, or traditional medicines), and by being targeted for aquarium use. Although its listing on CITES Appendix II aims to regulate international trade to be sustainable, little is known about domestic trade, illegal and unreported trade, and the overall level of offtake from wild populations. Fishers have also recorded substantial declines in seahorses through much of this species' range. Based on fisher interview data and national listings in Colombia, Venezuela, and Brazil, it is inferred that that this species has declined by more than 30% through most of its range, with declines ongoing. Populations in the Gulf of Mexico appear to be much more stable. Overall, it is inferred that this species has undergone declines approaching 30% which are still ongoing, and therefore H. reidi is listed as Near Threatened.
|Previously published Red List assessments:|
|Range Description:||Hippocampus reidi inhabits coastal waters in the western Atlantic from North Carolina south along the U.S., throughout the Gulf of Mexico and Caribbean Sea, and along South America to southern Brazil (Musick et al. 2000, Hercos and Giarrizzo 2007, Silveira et al. 2014, R. Robertson pers. comm. 2014). Its depth range is 0-55 m (Vari 1982).|
Native:Bahamas; Barbados; Belize; Bermuda; Brazil (Alagoas, Amapá, Bahia, Ceará, Espírito Santo, Maranhão, Pará, Paraíba, Paraná, Pernambuco, Piauí, Rio de Janeiro, Rio Grande do Norte, Rio Grande do Sul, Santa Catarina, São Paulo, Sergipe); Cayman Islands; Colombia (Colombia (mainland), Colombian Caribbean Is.); Costa Rica (Costa Rica (mainland)); Cuba; Dominica; Grenada; Guadeloupe; Haiti; Honduras (Honduran Caribbean Is., Honduras (mainland)); Jamaica; Mexico (Veracruz, Yucatán); Panama; Puerto Rico (Puerto Rico (main island)); Saint Lucia; Saint Vincent and the Grenadines; Suriname; Trinidad and Tobago; Turks and Caicos Islands; United States (Florida, North Carolina); Venezuela, Bolivarian Republic of (Venezuela (mainland), Venezuelan Antilles); Virgin Islands, British; Virgin Islands, U.S.
|FAO Marine Fishing Areas:|
Atlantic – western central; Atlantic – southwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||During Project Seahorse trade surveys conducted between 2000–2001, fishers in Brazil, Guatemala, Honduras, Mexico, Nicaragua and Panama reported decreases in the catch of seahorses in general both in trawls (as bycatch) and by divers (J. Baum and I. Rosa, unpublished data), but the portion of these declines attributable to H. reidi is unknown. |
From October 2005 to September 2006, monthly samplings were carried out at the Mamanguape estuary, State of Paraíba, in northeastern Brazil and a total of 280 seahorses were sampled (Castro et al. 2008); at the Camurupim/Cardoso estuary, Piauí, NE Brazil, 647 specimens were sampled (Mai and Rosa 2009); and at twelve Brazilian locations, 911 specimens were recorded from 2002 to 2006.
In Brazilian estuaries, H. reidi presented a mean density of 0.026 specimens/m², ranging from 0.0023-0.066 specimens/m² at sampled localities from 2002 to 2006 (Rosa et al. 2007, Mai and Rosa 2009). Lower densities were found at localities where trade was recorded (mean 0.013 specimens/m²) than in locations where no trade took place (mean 0.04 specimens/m²) (Rosa et al. 2007). At rocky shores in Rio de Janeiro state, mean densities could vary from 0.001 to 0.04 specimens/m² (Freret-Meurer and Andreata 2008, Oliveira and Freret-Meurer 2012). From December 2002 to November 2004 the population density of H. reidi at Araçatiba beach, which is in an Environmental Protection Area at Ilha Grande in Rio de Janeiro, significantly decreased during the two years of study. The difference in density during each month in the first and second year was more than half in most months (Freret-Meurer and Andreata 2008). Declines were reported by fishermen in several localities in at least five NE Brazilian states; in some localities, declines could reach up to 90% over the course of a decade (Rosa et al. 2005, 2011). Declines were also reported by vendors of zootherapeutic products in NE Brazil (Ferreira et al. 2012). Local extirpation has been reported in some locations (Rosa et al. 2011).
Declines were also reported in Colombia (Pineda et al. 2006), but their extent is unknown. In Cuba, from 2004 to 2005, mean density ranged from 0.01 to 0.0037 specimens/m² (Gutiérrez et al. 2011).
This species is listed as VU in national assessments throughout at least 30% of its range, with declines exceeding 30% (Brazil, Venezuela, and Colombia). The only place where it is thought to be stable is in US waters, particularly in the Gulf of Mexico. Although population trends over the entire population have not been quantified, we infer declines at rates approaching 30% over the past 10 years based on the substantial ongoing local declines that have been documented.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||Hippocampus reidi inhabits a variety of coastal habitats and holdfast types, including invertebrates such as bryozoans, sponges, and tunicates, gorgonian corals, seagrasses, estuaries, and especially on macroalgae (often the genus Caulerpa), mangroves (Avicennia shaueriana, Laguncularia racemosa, and Rhizophora mangle) and on artificial structures such as piers (Dias and Rosa 2003, Rosa et al. 2007, Mai and Rosa 2009, Gutiérrez et al. 2011, Aylesworth et al. 2015). Vari (1982) reports H. reidi at depths as great as 55 m. Small individuals tend to be found in shallower water than large animals (Dauwe 1993). In Brazilian estuaries, H. reidi is commonly found at mean depths lower than 0.40 m (Rosa et al. 2007). Indeed, shallow waters, warm temperatures and higher number of mangrove structures could be used to predict seahorse presence in estuarine habitats, as well as calmer waters (Aylesworth et al. 2015). In rocky shores in Rio de Janeiro, Brazil, seahorses were mainly found at mean depths of 4.97 m (Oliveira and Freret-Meurer 2012). Hippocampus reidi is mostly found solitary, but mated pairs are common and the species was also recorded to form groups of up to seven individuals (Rosa et al. 2007, Mai and Rosa 2009). |
The species feeds on crustaceans such as harpacticoid, calanoid, and cyclopoid copepods, caridean shrimps, gammarid and caprellid amphipods, nematodes, and ostracods. Juveniles fed more heavily on hymenopteran insects and mollusk and crustacean eggs, and females relied heavily on caridean shrimps (Felicio et al. 2006, Castro et al. 2008). They are usually sit-and-wait predators but sometimes actively pursue their prey (Felicio et al. 2006).
As in other seahorses, this species is ovoviviparous, and the males brood the young in a pouch prior to giving live birth (Foster and Vincent 2004). Males matured at 9.5 cm but did not carry embryos until they were 12.4 cm, while mature females were recorded at lengths of 8.8 cm (Mai and Velasco 2011). A seven month 'resting period' was observed between pregnancies in Rio de Janeiro (Freret-Meurer and Andreata 2008). Hippocampus reidi are pair-bonded in the wild (B. Dauwe and M. Nijhoff in litt. to Lourie et al. 1999, Rosa et al. 2007). Reproduction occurs throughout the year but peak reproduction has been recorded from May- November in NE Brazil (Mai and Velasco 2011). Seahorse pairs were re-sighted in estuaries in Piauí and Rio Grande do Norte states, Brazil (Dias and Rosa 2003, Mai and Rosa 2009), and site fidelity and small home ranges reported in Brazil and in Cuba (Rosa et al. 2007, Mai and Rosa 2009, Mai and Velasco 2011, Hernández et al. 2016) suggest a monogamous sexual pattern.
The von Bertalanffy growth constant (k) was estimated at 1.195/yr and natural mortality ranged from 1.43 to 1.58/yr. Survival was calculated to be between 21% and 24%. Lifespan was estimated to be 2.5 years (Mai and Velasco 2011).
It was suggested that the availability of holdfasts could influence the spatial distribution of these seahorses (Dias and Rosa 2003, Aylesworth et al. 2015). The feeding behaviour of 57 specimens was recorded from May 2003 to September 2004 in estuarine habitats (Felicio et al. 2006) and 90 specimens had their activity rate evaluated at a rocky shore in SE Brazil, where pregnant males were found less active in relation to females and non-pregnant males (Freret-Meurer et al. 2012).
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Generation Length (years):||1|
|Movement patterns:||Not a Migrant|
|Use and Trade:||
Hippocampus reidi is retained as bycatch in industrial trawl fisheries and in artisanal small-scale fisheries, and is sometimes targeted live by divers for aquarium trade. It is one of the most widely held species of Hippocampus in public aquaria and is one of the most sought after seahorses in the international aquarium trade (Castro et al. 2008). The numbers of aquarium trade Hippocampus reidi that were traded internationally and recorded in the CITES trade database are 148,766 to 317,522 from captivity, 20,478 to 22-662 from the wild, and 2,476 from unknown origins (Koldewey and Martin-Smith 2010, Rosa et al. 2011). Between 2010 and 2014 annual reported export levels of H. reidi levelled off at just over 10 000 specimens (CITES 2016). Levels of domestic trade are unknown for most of the species' range.
Data from Brazil indicate that daily catches of live seahorses for the aquarium trade from January 1997–April 2004 led to an estimate of 715,000 live H. reidi that could be caught from wild populations annually in Brazil in that period (Rosa et al. 2011). Colourful (orange, yellow and red) specimens reached the highest prices; from 1997 to 2005, fishers were paid for a coloured seahorse a mean of US$1.23, while black and brown specimens had a mean price of US$1.04; coloured seahorses retail mean price was US$12.27, and dark coloured US$9.64 (Rosa et al. 2011). Daily catches of live seahorses for the aquarium trade in Brazil from January/1997–April/2004 led to an estimate of 715,000 live H. reidi that could be caught from wild populations annually in Brazil in that period (Rosa et al. 2011). Colourful (orange, yellow and red) specimens reached the highest prices; from 1997 to 2005, fishers were paid for a coloured seahorse a mean of US$1.23, while black and brown specimens had a mean price of US$1.04; coloured seahorses retail mean price was US$12.27, and dark coloured US$9.64 (Rosa et al. 2011).
The dried seahorse trade has no formal records in Brazil. Domestic trade data are available from interviews (n = 92) conducted with fishers and end-sellers from 2002 to 2009 (Rosa et al. 2011). The main source of dried H. reidi seahorses was the non-industrial bycatch in N-NE Brazil; trade volumes were estimated at a mean of 29.7 seahorses sold per month per trader, and a mean of 356.4 dried seahorses sold annually per trader (Rosa et al. 2011).Dried seahorses were usually sold unadorned or as key chains. Occasionally some of them were sold as jewelry, shell crafts with shells and sea stars, or as 'dragons' with wings and eyes attached. These dried seahorses were sometimes ground and consumed in a drink as folk medicine to treat almost 30 diseases and health conditions (Rosa et al. 2013), including asthma, bronchitis, gastritis, baldness, wounds, and tuberculosis (Baum and Vincent 2005; Rosa et al. 2011, 2013; El Deir et al. 2012). Chinese populations in Panama and Peru sold seahorses commercially as medicine, for use as TCM. Dried seahorses have also been sold in Brazil for magic-religious purposes, in the form of “seahorse perfume” and amulets (called “pautás”), used to bring protection, good luck and to avoid evil eye, and also to attract emotional and financial success (Alves et al. 2012).
The live seahorses were traded as aquarium fishes. Also, in some countries, including Honduras and Costa Rica, they have in situ value because dive masters would take tourists to particular sites where these seahorses were located (Baum and Vincent 2005). In Brazil, this activity is unregulated and performed in at least three NE states (Piauí, Ceará and Pernambuco), under the name of “passeio do cavalo-marinho”, in which seahorses are captured by “guides” and displayed for tourists in plastic or glass jars. There is no scientific impact assessment of this activity in the country (Ministério do Meio Ambiente 2011).
Levels of overall offtake from wild populations are unknown, but are thought to number at least in the 10s of thousands. The magnitude of the impacts of this use and trade on wild populations is not known.
Hippocampus reidi is threatened by being caught as bycatch in trawl and artisanal fisheries (e.g. Branco et al. 2015). It is also heavily targeted for the aquarium trade, where fishers have reported substantial declines (Rosa et al. 2011). The species may also be suffering as a result of mangrove, coral and seagrass habitat degradation and loss (Karnauskas et al. 2013, Jackson et al. 2014). Particularly, it is potentially susceptible to habitat degradation due to its strong relationship with mangrove structures (Aylesworth et al. 2015). Experiments show that crude oil and hypoxia events in the Gulf of Mexico result in DNA damage and detrimental morphological functioning of H. reidi, but population impacts are not known (Negreiros et al. 2011).
This species is considered threatened in the United States by the American Fisheries Society (Musick et al. 2000). They cite the species' rarity and degradation of its seagrass habitats in South Florida as reasons for this listing. Moreover, H. reidi is considered Vulnerable in Venezuela (Ron et al. 2015), Colombia (Ministerio de Ambiente, Vivienda y Desarrollo Territorial, 2010) and Brazil (IBAMA 2014). In the latter, the species is also listed as vulnerable in red lists of four states (Espírito Santo, Rio de Janeiro, Paraná and Santa Catarina); in São Paulo, it is considered a species in need of fisheries management and policies for its conservation. In Mexico, it is listed on Mexico’s NOM-059-SEMARNAT-2001 as a species subject to special protection.
There are no species-specific conservation measures in place for Hippocampus reidi. The entire genus Hippocampus was listed on Appendix II of CITES in 2004. In Mexico, it is listed on Mexico’s NOM-059-SEMARNAT-2001 as a species subject to special protection. Permits or licenses are required to export dried syngnathids from Honduras and Nicaragua, and to export live syngnathids from Panama, Brazil, Costa Rica, Guatemala and Nicaragua. In Brazil, other general measures that may benefit seahorses include a marine ornamental fishes Trade Database, the delimitation of specific airports through which wildlife can be exported, and the publication of an illustrated handbook of marine ornamental fishes by IBAMA (Sampaio and Nottingham 2008). Moreover, only registered fishers are allowed to collect marine ornamental fishes, and only professional fishers have authorisation to sell them, according to the Brazilian legislation applied to marine ornamental fishes (Rosa et al. 2011). All seahorse species in Brazil are included in the Plano de Ação Nacional para a Conservação dos Ambientes Coralíneos – PAN Corais, which establishes priority conservation strategies for threatened fishes and aquatic invertebrates (ICMBIO 2016).
There are annual quotas in Brazil of 250 specimens per company for the live trade (Rosa et al. 2011), although misidentifications as H. erectus may occur (Rosa et al. 2011). In 2004, seahorses were included in the National List of the Aquatic Invertebrates and Fish Species Overexploited or Threatened of Overexploitation (Ministério do Meio Ambiente 2004), which resulted in the publication, in 2011, of a proposal of management plan for the sustainable use of the Brazilian seahorse species. Specifically, the main objectives towards H. reidi were the recovery and maintenance of wild populations and preferred habitats (Ministério do Meio Ambiente 2011). The species distribution falls within several marine protected areas in Brazil (Rosa et al. 2007, Mai and Rosa 2009); indeed, some of these were created for and/or improved for seahorse conservation, such those that include the Rio Mamanguape estuary (Paraíba state) and the Rio Tubarão estuary (Rio Grande do Norte state).
|Citation:||Oliveira, T. & Pollom, R. 2017. Hippocampus reidi. The IUCN Red List of Threatened Species 2017: e.T10082A17025021.Downloaded on 19 July 2018.|
|Feedback:||If you see any errors or have any questions or suggestions on what is shown on this page, please provide us with feedback so that we can correct or extend the information provided| | <urn:uuid:20190f56-5377-424b-81d3-a7d03e093a98> | 2.578125 | 4,387 | Knowledge Article | Science & Tech. | 49.720952 | 95,508,448 |
Saturn's southern hemisphere shows dark spots and wisps of high clouds in this image. Note the boomerang shape of the patterns in the mid-latitude bands. The image was taken with the Cassini narrow angle camera in the near infrared on May 8, 2004, from a distance of 28.1million kilometers (17.5 million miles). Image scale is 168 kilometers (104 miles) per pixel. The image has been enhanced to aid visibility. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras, were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo. For more information, about the Cassini-Huygens mission visit, <a href="http://saturn.jpl.nasa.gov/">http://saturn.jpl.nasa.gov</a> and the Cassini imaging team home page, <a href="http://ciclops.org/">http://ciclops.org</a>. | <urn:uuid:31562ad0-2ea1-4a6b-bd0b-5cd8eb794249> | 3.390625 | 280 | Knowledge Article | Science & Tech. | 53.20629 | 95,508,450 |
1. Park rangers catch, tag, and then release 140 elk back into a national park. One month later, they select a sample of 130 elk, 91 of which are tagged. Assuming the ratio of tagged elk in the sample holds for all elk in the park, approximately how many elk are in the park?
2. The formula M = 0.0075x2 - 0.2676x + 14.8 models the fuel efficiency of passenger cars, M, in miles per gallon, x years after 1940. Environmentalists pressured automobile manufactures for a fuel efficiency of 45 miles per gallon by the year 2000. In which year will the fuel efficiency reach 45 miles per gallon according to the formula?© BrainMass Inc. brainmass.com July 19, 2018, 6:03 am ad1c9bdddf
Ratio and proportion problems are solved. | <urn:uuid:f41b643b-617c-4b44-bb5f-e180c6af3f08> | 3.21875 | 182 | Q&A Forum | Science & Tech. | 79.620769 | 95,508,451 |